Using DNA to Solve Cold Case - Imprimus Forensic Services

JULY 02Using DNA to Solve Cold CasesNCJ 194197

National Commission on theFuture of DNA EvidenceIn 1995, the National Institute of Justice(NIJ) began research that would attemptto identify how often DNA had exoneratedwrongfully convicted defendants. Afterextensive study, NIJ published the reportConvicted by Juries, Exonerated byScience: Case Studies in the Use of DNAEvidence to Establish Innocence AfterTrial, which presents case studies of 28inmates for whom DNA analysis wasexculpatory.On learning of the breadth and scope ofthe issues related to forensic DNA, theAttorney General asked NIJ to establishthe National Commission on the Future ofDNA Evidence as a means to examine themost effective use of DNA in the criminaljustice system. The Commission wasappointed by the NIJ Director and representedthe broad spectrum of the criminaljustice system. Chaired by the HonorableShirley S. Abrahamson, Chief Justice ofthe Wisconsin Supreme Court, the Commissionconsisted of representatives fromthe prosecution, the defense bar, lawenforcement, the scientific community,the medical examiner community, academia,and victims’ rights organizations.The Commission’s charge was to submitrecommendations to the Attorney Generalthat will help ensure the best use of DNAas a crimefighting tool and foster its usethroughout the entire criminal justicesystem. Other focal areas for the Commission’sconsideration included crimescene investigation and evidencecollection, laboratory funding, legal issues,and research and development. TheCommission’s working groups, consistingof commissioners and other experts,researched and examined various topicsand reported back to the Commission. Theworking groups’ reports were submittedto the full Commission for approval,amendment, or further discussion and providedthe Commission with backgroundfor its recommendations to the AttorneyGeneral.By nature of its representative compositionand its use of numerous working groups,the Commission received valuable inputfrom all areas of the criminal justice system.The broad scope of that input enabledthe Commission to develop recommendationsthat both maximize the investigativevalue of the technology and address theissues raised by its application.Commission membersChairThe Honorable Shirley S. AbrahamsonChief JusticeWisconsin Supreme CourtMembersDwight E. AdamsDirectorFederal Bureau of Investigation Laboratoryiii

SPECIAL REPORT / JULY 02Jan S. BashinskiChiefBureau of Forensic ServicesCalifornia Department of JusticeSacramento, CaliforniaGeorge W. ClarkeDeputy District AttorneySan Diego, CaliforniaJames F. CrowProfessorDepartment of GeneticsUniversity of WisconsinLloyd N. CutlerWilmer, Cutler & PickeringWashington, D.C.Joseph H. DavisFormer DirectorMiami-Dade Medical ExaminerDepartmentPaul B. FerraraDirectorDivision of Forensic SciencesCommonwealth of VirginiaNorman GahnAssistant District AttorneyMilwaukee County, WisconsinTerrance W. GainerExecutive Assistant ChiefMetropolitan Police DepartmentWashington, D.C.Terry G. HillardSuperintendent of PoliceChicago Police DepartmentChicago, IllinoisAaron D. KennardSheriffSalt Lake County, UtahRonald S. ReinsteinAssociate Presiding JudgeSuperior Court of ArizonaMaricopa County, ArizonaDarrell L. SandersChiefFrankfort Police DepartmentFrankfort, IllinoisBarry C. ScheckProfessorCardozo Law SchoolNew York, New YorkMichael SmithProfessorUniversity of Wisconsin Law SchoolJeffrey E. ThomaPublic DefenderMendocino County, CaliforniaKathryn M. TurmanDirectorOffice for Victim AssistanceFederal Bureau of InvestigationWilliam WebsterMilbank, Tweed, Hadley & McCloyWashington, D.C.James R. WooleyBaker & HostetlerCleveland, OhioCommission staffChristopher H. AsplenExecutive DirectorLisa FormanDeputy DirectorRobin W. JonesExecutive AssistantPhilip ReillyInterleukin GeneticsWaltham, Massachusettsiv

USING DNA TO SOLVE COLD CASESCrime Scene InvestigationWorking GroupThe Crime Scene Investigation WorkingGroup is a multidisciplinary group of criminaljustice professionals from across the UnitedStates who represent both urban and ruraljurisdictions. Working group members andcontributors were recommended andselected for their experience in the area ofcriminal investigation and evidence collectionfrom the standpoints of law enforcement,prosecution, defense, the forensiclaboratory, and victim assistance.DNA has proven to be a powerful tool inthe fight against crime. DNA evidence canidentify suspects, convict the guilty, andexonerate the innocent. Throughout theNation, criminal justice professionals arediscovering that advancements in DNAtechnology are breathing new life into old,cold, or unsolved criminal cases. Evidencethat was previously unsuitable for DNAtesting because a biological sample wastoo small or degraded may now yield aDNA profile. Development of the CombinedDNA Index System (CODIS) at theState and national levels enables lawenforcement to aid investigations by effectivelyand efficiently identifying suspectsand linking serial crimes to each other. TheNational Commission on the Future ofDNA Evidence made clear, however, thatwe must dedicate more resources toempower law enforcement to use thistechnology quickly and effectively.Using DNA to Solve Cold Cases is intendedfor use by law enforcement and othercriminal justice professionals who havethe responsibility for reviewing and investigatingunsolved cases. This report willprovide basic information to assist agenciesin the complex process of casereview with a specific emphasis on usingDNA evidence to solve previously unsolvablecrimes. Although DNA is not theonly forensic tool that can be valuable tounsolved case investigations, advancementsin DNA technology and the successof DNA database systems have inspiredlaw enforcement agencies throughout thecountry to reevaluate cold cases for DNAevidence. As law enforcement professionalsprogress through investigations, however,they should keep in mind the array ofother technology advancements, such asimproved ballistics and fingerprint databases,which may substantially advancea case beyond its original level.ChairTerrance W. GainerExecutive Assistant ChiefMetropolitan Police DepartmentWashington, D.C.MembersSusan BallouOffice of Law Enforcement StandardsNational Institute of Standards andTechnologyGaithersburg, MarylandJan S. BashinskiChiefBureau of Forensic ServicesCalifornia Department of JusticeSacramento, CaliforniaSue BrownINOVA Fairfax HospitalSANE ProgramFalls Church, Virginiav

SPECIAL REPORT / JULY 02Lee ColwellDirectorCriminal Justice InstituteUniversity of Arkansas SystemLittle Rock, ArkansasThomas J. CroninChiefCity of Coeur d’Alene Police DepartmentCoeur d’Alene, IdahoTerry G. HillardSuperintendent of PoliceChicago Police DepartmentChicago, IllinoisMark JohnseyMaster Sergeant (Ret.)Division of Forensic ServicesIllinois State Police DepartmentSpringfield, IllinoisChristopher PlourdAttorney at LawSan Diego, CaliforniaDarrell L. SandersChiefFrankfort Police DepartmentFrankfort, IllinoisClay StrangeAssistant District AttorneyTravis County District Attorney’s OfficeAustin, TexasContributorsCheryl MayAssistant DirectorForensic Sciences Education CenterLittle Rock, ArkansasWilliam McIntyreDetective Sergeant (Ret.)Atlantic County Prosecutor’s OfficeHomicide UnitHammonton, New Jerseyvi

ContentsNational Commission on the Future of DNA Evidence . . . . . . . . . . . . . . . . . . . . . iiiIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1The Long and Short of DNA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5How Can DNA Databases Aid Investigations? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Practical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Identifying, Analyzing, and Prioritizing Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17vii

IntroductionIn 1990, a series of brutal attacks on elderlyvictims occurred in Goldsboro, NorthCarolina, by an unknown individual dubbedthe “Night Stalker.” During one suchattack in March, an elderly woman wasbrutally raped and almost murdered. Herdaughter’s early arrival home was the onlything that saved the woman’s life. Thesuspect fled, leaving behind materialsintended to burn the residence and thevictim in an attempt to conceal the crime.In July 1990, another elderly woman wasbrutally raped and murdered in her home.Three months later, a third elderly womanwas raped and stabbed to death. Her husbandwas also murdered. Their housewas burned in an attempt to cover up thecrime, but fire/rescue personnel pulledthe bodies from the house before it wasengulfed in flames.When DNA analysis was conducted onbiological evidence collected from vaginalswabs from each victim, authorities concludedthat the same perpetrator hadcommitted all three crimes. However,there was no suspect.For 10 years, both the Goldsboro PoliceDepartment and the crime laboratoryrefused to forget about these cases. Withfunding from the National Institute ofJustice, the crime laboratory retested thebiological evidence in all three cases withnewer DNA technology and entered theDNA profiles into North Carolina’s DNAdatabase. This would allow the DNA profiledeveloped from the crime scene evidenceto be compared to thousands ofconvicted offender profiles already in thedatabase.In April 2001, a “cold hit” was made tothe perpetrator’s convicted offender DNAprofile in the database. The perpetratorhad been convicted of shooting into anoccupied dwelling, an offense thatrequires inclusion in the North CarolinaDNA database. The suspect was broughtinto custody for questioning and wasserved with a search warrant to obtain asample of his blood. That sample was analyzedand compared to the crime sceneevidence, thereby confirming the DNAdatabase match. When confronted withthe DNA evidence, the suspect confessedto all three crimes.Mark Nelson, special agent in charge ofthe North Carolina State Crime Laboratory,said, “Even though these terrible crimesoccurred more than 10 years ago, wenever gave up hope of solving them oneday.”Every law enforcement departmentthroughout the country has unsolvedcases that could be solved through recentadvancements in DNA technology. Today,investigators who understand which evidencemay yield a DNA profile can identifya suspect in ways previously seen only ontelevision. Evidence invisible to the nakedeye can be the key to solving a residentialburglary, sexual assault, or murder. Thesaliva on the stamp of a stalker’s threateningletter, the perspiration on a rapist’smask, or the skin cells shed on the ligatureof a strangled child may hold the keyto solving a crime.In Austin, Texas, for example, an investigatorknowledgeable about DNA technologywas able to solve the rape of a localcollege student. Having read about thepotential for obtaining DNA evidence fromthe ligature used to strangle a victim, theinvestigator requested DNA testing on thephone cord used to choke the victim in hiscase. He realized that in the course of1

SPECIAL REPORT / JULY 02The successfulreview andinvestigation ofunsolved casesrequire cooperationamong lawenforcement, thecrime laboratory,and the prosecutor’soffice.choking someone, enough force and frictionis applied to the rope or cord that theperpetrator’s skins cells may rub off hishands and be left on the ligature.The investigator’s request paid off in anunanticipated way. In spite of the attacker’sattempt to avoid identification throughDNA evidence by wearing both a condomand rubber gloves, a reliable DNA profilewas developed from the evidence. Duringthe struggle, the attacker was forced touse one hand to hold the victim down,leaving only one hand to pull the phonecord tight. The attacker had to grab theremaining end of the cord with his mouth,thereby depositing his saliva on the cord.Although the developed profile came fromsaliva rather than skin, DNA not onlysolved the case in Austin, but also linkedthe perpetrator to a similar sexual assaultin Waco.Without the investigator’s understandingof DNA technology and where DNA mightbe found, the case may have goneunsolved. The successful review andinvestigation of unsolved cases requirethe same basic elements as the investigationof new cases: cooperation among lawenforcement, the crime laboratory, andthe prosecutor’s office. Investigatorsshould be aware of technologicaladvances in DNA testing that may yieldprofiles where previous testing was notperformed or was unsuccessful. Thecrime laboratory can be essential to thepreliminary review of unsolved cases, forexample, by providing investigators withlaboratory reports from previous testingand consultation regarding the investigativevalue of new DNA analysis techniquesand DNA database search capabilities.Additionally, the prosecutor’s office shouldbe involved as soon as a case is reopenedso that legal issues are addressed appropriately.It is also extremely important thatcase reconstruction considers the victimor victim’s family and the importance offinality to closing a case.Although DNA is not the only forensic toolavailable for the investigation of unsolvedcases, advancements in DNA testing andthe success of DNA database systemshave inspired law enforcement agenciesthroughout the country to reevaluatecases previously thought unsolvable. Thepurpose of this report is to provide lawenforcement with a practical resource forthe review of old, cold, or unsolved casesthat may be solved through DNA technologyand DNA databases. “The Long andShort of DNA” and “How Can DNADatabases Aid Investigations?” will educatethe reader about the science andtechnology of DNA testing and DNA databases.“Practical Considerations” providesimportant background information on legaland practical considerations regarding theapplication of DNA technology to old, cold,or unsolved cases. Finally, a step-by-stepprocess is provided to help investigatorsselect cases that would most likely besolved with DNA evidence. As investigatorsadvance through this process, theyshould also keep in mind the array ofother technology advancements, such asimproved ballistics and fingerprint databases,that may benefit their investigation.Advancements inDNA technologyAdvancements in DNA analysis, togetherwith computer technology and theCombined DNA Index System (CODIS), 1have created a powerful crimefighting toolfor law enforcement. CODIS is a computernetwork that connects forensic DNAlaboratories at the local, State, and nationallevels. DNA database systems that useCODIS contain two main criminal indexesand a missing persons index. When aDNA profile is developed from crimescene evidence and entered into theforensic (crime scene) index of CODIS,the database software searches thousandsof convicted offender DNA profiles2

USING DNA TO SOLVE COLD CASES(contained in the offender index) of individualsconvicted of offenses such as rapeand murder. Similar to the AutomatedFingerprint Identification System (AFIS),CODIS can aid investigations by efficientlycomparing a DNA profile generated frombiological evidence left at a crime sceneagainst convicted offender DNA profilesand forensic evidence from other casescontained in CODIS. CODIS can also aidinvestigations by searching the missingpersons index, which contains DNA profilesof unidentified remains and DNA profilesof relatives of those who are missing.Because of the recidivistic nature of violentoffenders, the power of a DNA databasesystem is evident not only in thesuccess of solving crimes previouslythought unsolvable, but perhaps moreimportantly, through the prevention ofcrime.When properly documented, collected, andstored, biological evidence can be analyzedto produce a reliable DNA profile years,even decades, after it is collected. Just asevidence collected from a crime thatoccurred yesterday can be analyzed forDNA, today evidence from an old rape kit,bloody shirt, or stained bedclothes maycontain a valuable DNA profile. These newanalysis techniques, in combination with anevolving database system, make a powerfulargument for the reevaluation of unsolvedcrimes for potential DNA evidence.Knowledgeable law enforcement officersare taking advantage of powerful DNAanalysis techniques by investigating crimescenes with a keener eye toward biologicalevidence. The same new approachbeing applied to crime scene processingand current case investigation can beapplied to older unsolved cases. Lawenforcement agencies across the countryare establishing cold-case squads to systematicallyreview old cases for DNA andother new leads. This report will serve asa resource to assist law enforcement withmaximizing the potential of DNA evidencein unsolved cases by covering the basicsof DNA analysis and its application toforensic casework. The report will alsodemonstrate how DNA database systems,advancing technology, and cooperativeefforts can enhance unsolved case investigativetechniques.New lawsAdvancements in DNA technology haveled to significant changes in many States’statutes, which may affect the manner inwhich unsolved cases are investigated,filed, and prosecuted. Advancements inthe technology have been so significantthat laws are being created, amended, andeven repealed to take advantage of itsability to identify and convict the guilty andexonerate the innocent. Laws regardingDNA admissibility in court, its use in postconvictionappeals, the creation andexpansion of databases, and the extensionor elimination of statutes of limitation areexamples of the quickly evolving impact ofDNA on the criminal justice system. Giventhe legal changes occurring throughoutthe country, constant contact and consultationwith the local prosecutor is criticalnot only for the investigation of oldercases but for all cases in which DNA maybe relevant evidence.Statutes of limitationStatutes of limitation may be one of themost difficult issues to overcome whenexamining older cases. Statutes of limitationestablish time limits under whichcriminal charges can be filed for a particularoffense. These statutes are rooted inthe protection of individuals from the useof evidence that becomes less reliableover time. For example, witnesses’ memoriesfade as time goes by. However,although some evidence, such as eyewitnessaccounts, can lose credibility overtime, DNA evidence has the power todetermine truth 10, 15, even 20 yearsThe power of aDNA databasesystem is evidentnot only in thesuccess ofsolving crimespreviously thoughtunsolvable, butthrough thepreventionof crime.3

SPECIAL REPORT / JULY 02The reliability ofDNA technologymay necessitatethe reevaluationof statutesof limitation.after an offense is committed. States arebeginning to realize that the reliability ofDNA technology may necessitate thereevaluation of statutes of limitation in thefiling of cases.Database expansionThe use of DNA evidence and convictedoffender DNA databases has expandedsignificantly since the first U.S. DNA databasewas created in 1989. Although Stateand local DNA databases established inthe early 1990s contained only DNA profilesfrom convicted murderers and sexoffenders, the undeniable success of DNAdatabases has resulted in a national trendtoward database expansion. All Statesrequire at least some convicted offendersto provide a DNA sample to be collectedfor DNA profiling and, in 2000, the FederalGovernment began requiring certainoffenders convicted of Federal or militarycrimes to also provide a DNA sample forthe criminal DNA database. Recognizingthat the effectiveness of the DNA databaserelies on the volume of data containedin both the forensic index (crimescene samples) and the convicted offenderindex of CODIS, many States arechanging their database statutes toinclude less violent criminals. ManyStates are enacting legislation to requireall convicted felons to submit a DNA profileto the State database. The tendencyfor States to include all convicted felons intheir databases dramatically increases thenumber of convicted offender DNA profilesagainst which forensic DNA evidencecan be compared, thus making the databasesystem a more powerful tool for lawenforcement.New legal approachesDNA technology and DNA databases haveencouraged the development of newapproaches to old cases. One suchapproach is the filing of charges by “JohnDoe” warrant. These warrants are basedon the unique DNA profile obtained fromthe analysis of unsolved crime scene evidence.Although John Doe warrants aretraditionally filed based on the physicaldescription or alias of an unnamed suspect,investigators and prosecutors arenow filing charges using the suspect’sDNA profile as the identifier. This innovativeapproach has allowed charges to befiled that toll and permit old cases to beprosecuted when the person matching theJohn Doe DNA profile is identified. JohnDoe DNA warrants are one way to permitcases to remain active, allowing them thechance to be solved through the DNAdatabase in the future.4

The Long and Short of DNAIf biologicalevidence isavailable fortesting orretesting inunsolved caseinvestigations, itis important thatlaw enforcementand the crimelaboratory worktogether toreview evidence.DNA is the fundamental building block foran individual’s entire genetic makeup. It isa component of virtually every cell in thehuman body, and a person’s DNA is thesame in every cell. That is, the DNA in aperson’s blood is the same as the DNA inhis skin cells, saliva, and other biologicalmaterial.DNA analysis is a powerful tool becauseeach person’s DNA is unique (with theexception of identical twins). Therefore,DNA evidence collected from a crimescene can implicate or eliminate a suspect,similar to the use of fingerprints. Italso can analyze unidentified remainsthrough comparisons with DNA from relatives.Additionally, when evidence fromone crime scene is compared with evidencefrom another using CODIS, thosecrime scenes can be linked to the sameperpetrator locally, statewide, andnationally.DNA is also a powerful tool because whenbiological evidence from crime scenes iscollected and stored properly, forensicallyvaluable DNA can be found on evidencethat may be decades old. Therefore, oldcases that were previously thought unsolvablemay contain valuable DNA evidencecapable of identifying the perpetrator.Similar to fingerprintsDNA is often compared with fingerprintsin the way matches are determined.When using either DNA or fingerprints toidentify a suspect, the evidence collectedfrom the crime scene is compared with a“known” standard. If identifying featuresare the same, the DNA or fingerprint canbe determined to be a match. However, ifidentifying features of the DNA profile orfingerprint are different from the knownstandard, it can be determined that it didnot come from that known individual.DNA technologyadvancementsRecent advancements in DNA technologyhave improved law enforcement’s abilityto use DNA to solve old cases. Originalforensic applications of DNA analysis weredeveloped using a technology calledrestriction fragment length polymorphism(RFLP). Although very old cases (morethan 10 years) may not have had RFLPanalysis done, this kind of DNA testingmay have been attempted on more recentunsolved cases. However, because RFLPanalysis required a relatively large quantityof DNA, testing may not have been successful.Similarly, biological evidencedeemed insufficient in size for testing maynot have been previously submitted fortesting. Also, if a biological sample wasdegraded by environmental factors suchas dirt or mold, RFLP analysis may havebeen unsuccessful at yielding a result.Newer technologies could now be successfulin obtaining results.Newer DNA analysis techniques enablelaboratories to develop profiles from biologicalevidence invisible to the naked eye,such as skin cells left on ligatures orweapons. Unsolved cases should be evaluatedby investigating both traditional andnontraditional sources of DNA. ValuableDNA evidence might be available that previouslywent undetected in the originalinvestigation.If biological evidence is available for testingor retesting in unsolved case investigations,it is important that law enforcementand the crime laboratory work togetherto review evidence. Logistical issues5

SPECIAL REPORT / JULY 02FingerprintsDNA StrandsIf the convictedoffender orforensic indexof CODIS is tobe used in theinvestigativestages of anunsolved case,DNA profiles mustbe generatedusing STRanalysis.regarding access to and the cost of DNAanalysis will be a factor, as well as issuesthat relate to the discriminating power ofeach technology and that might affect theoutcome of the results. Laboratory personnelcan also provide a valuable perspectiveon which evidence might yieldvaluable and probative DNA results.Finally, if previously tested biological evidenceproduced a DNA profile but excludedthe original suspect, revisiting those“exclusion” cases in the context of comparingthem with DNA databases mightprove to be very valuable to solving oldcases.PCR analysisPCR (polymerase chain reaction) enhancesDNA analysis and has enabled laboratoriesto develop DNA profiles from extremelysmall samples of biological evidence. ThePCR technique replicates exact copies ofDNA contained in a biological evidencesample without affecting the original,much like a copy machine. RFLP analysisrequires a biological sample about the sizeof a quarter, but PCR can be used toreproduce millions of copies of the DNAcontained in a few skin cells. Since PCRanalysis requires only a minute quantity ofDNA, it can enable the laboratory to analyzehighly degraded evidence for DNA.On the other hand, because the sensitivePCR technique replicates any and all ofthe DNA contained in an evidence sample,greater attention to contamination issuesis necessary when identifying, collecting,and preserving DNA evidence. These factorsmay be particularly important in theevaluation of unsolved cases in which evidencemight have been improperly collectedor stored.STR analysisShort tandem repeat (STR) technology is aforensic analysis that evaluates specificregions (loci) that are found on nuclearDNA. The variable (polymorphic) nature ofthe STR regions that are analyzed forforensic testing intensifies the discriminationbetween one DNA profile and another.For example, the likelihood that anytwo individuals (except identical twins) willhave the same 13-loci DNA profile can beas high as 1 in 1 billion or greater. TheFederal Bureau of Investigation (FBI) haschosen 13 specific STR loci to serve asthe standard for CODIS. The purpose ofestablishing a core set of STR loci is toensure that all forensic laboratories canestablish uniform DNA databases and,more importantly, share valuable forensicinformation. If the forensic or convictedoffender CODIS index is to be used in theinvestigative stages of unsolved cases,DNA profiles must be generated by usingSTR technology and the specific 13 coreSTR loci selected by the FBI.Mitochondrial DNA analysisMitochondrial DNA (mtDNA) analysisallows forensic laboratories to developDNA profiles from evidence that may notbe suitable for RFLP or STR analysis.While RFLP and PCR techniques analyzeDNA extracted from the nucleus of a cell,mtDNA technology analyzes DNA found ina different part of the cell, the mitochondrion(see exhibit 1). Old remains and evidencelacking nucleated cells—such ashair shafts, bones, and teeth—that areunamenable to STR and RFLP testing mayyield results if mtDNA analysis is performed.For this reason, mtDNA testingcan be very valuable to the investigation ofan unsolved case. For example, a coldcase log may show that biological evidencein the form of blood, semen, andhair was collected in a particular case, butthat all were improperly stored for a longperiod of time. Although PCR analysissometimes enables the crime laboratoryto generate a DNA profile from verydegraded evidence, it is possible that theblood and semen would be so highlydegraded that nuclear DNA analysis wouldnot yield a DNA profile. However, the hair6

USING DNA TO SOLVE COLD CASESshaft could be subjected to mtDNA analysisand thus be the key to solving thecase. Finally, it is important to note that allmaternal relatives (for example, a person’smother or maternal grandmother) haveidentical mtDNA. This enables unidentifiedremains to be analyzed and compared tothe mtDNA profile of any maternal relativefor the purpose of aiding missing personsor unidentified remains investigations.Although mtDNA analysis can be veryvaluable to the investigation of criminalcases, laboratory personnel should alwaysbe involved in the process.Exhibit 1. Cell diagramMitochondrionNucleusChromosomesY-chromosome analysisSeveral genetic markers have been identifiedon the Y chromosome that canbe used in forensic applications. Y-chromosome markers target only themale fraction of a biological sample.Therefore, this technique can be veryvaluable if the laboratory detects complexmixtures (multiple male contributors) withina biological evidence sample. Becausethe Y chromosome is transmitted directlyfrom a father to all of his sons, it can alsobe used to trace family relationshipsamong males. Advancements in Y-chromosometesting may eventually eliminate theneed for laboratories to extract and separatesemen and vaginal cells (for example,from a vaginal swab of a rape kit) prior toanalysis.Cooperative efforts with the crime laboratoryare essential to deciding which analysismethods will be most valuable in aparticular case. It is important to note,however, that while RFLP and mtDNA testingmay be valuable to the investigation ofan old case, current DNA databases arebeing populated with DNA profiles that aregenerated using STR analysis. RFLP andmtDNA profiles are not compatible withthe convicted offender or forensic indexesof CODIS. 27

How Can DNA DatabasesAid Investigations?SUCCESS STORYThe development and expansion of databasesthat contain DNA profiles at thelocal, State, and national levels have greatlyenhanced law enforcement’s ability tosolve cold cases with DNA. Convictedoffender databases store hundreds ofthousands of potential suspect DNAprofiles, against which DNA profilesdeveloped from crime scene evidencecan be compared.A “forensic hit” occurred in the National DNA Index System (NDIS) that linkeda dead Florida man’s DNA profile to eight serial unsolved rapes in Washington,D.C. and three offenses in Florida.In 1999, Leon Dundas was killed in a drug deal. Investigators rememberedDundas refusing to give a blood sample in connection with a rape investigationin 1998. They were able to obtain Dundas’ blood sample through the medicalexaminer’s office and forwarded it to the DNA lab at the Florida Department ofLaw Enforcement. Dundas’ DNA profile was compared with the national forensicindex and a match was made between Dundas and DNA evidence from arape victim in Washington, D.C.The FBI then entered DNA evidence from additional unsolved rapes committedin Washington. Dundas’ DNA matched seven additional rapes in Washingtonand three more in Jacksonville, Florida. Police in Washington said that withoutDNA, they would have never identified Dundas, who had no prior recorded historyof violent crime.Given the recidivistic nature of manycrimes, such as sexual assault and burglary,a likelihood exists that the individualwho committed the crime being investigatedwas convicted of a similar crime andalready has his or her DNA profile in aDNA database that can be searched byCODIS. Moreover, CODIS also permits thecross-comparison of DNA profiles developedfrom biological evidence found atcrime scenes. Even if a perpetrator is notidentified through the database, crimesmay be linked to each other, thereby aidingan investigation, which may eventuallylead to the identification of a suspect.What is CODIS?CODIS is a computer software programthat operates local, State, and nationaldatabases of DNA profiles from convictedoffenders, unsolved crime scene evidence,and missing persons. Every Statein the Nation has a statutory provision forthe establishment of a DNA database thatallows for the collection of DNA profilesfrom offenders convicted of particularcrimes. CODIS software enables State,local, and national law enforcement crimelaboratories to compare DNA profiles electronically,thereby linking serial crimes toeach other and identifying suspects bymatching DNA profiles from crime sceneswith profiles from convicted offenders.The success of CODIS is demonstrated bythe thousands of matches that have linkedserial cases to each other and cases thathave been solved by matching crimescene evidence to known convictedoffenders.The missing persons index consists of theunidentified persons index and the referenceindex. The unidentified personsindex contains DNA profiles from recoveredremains, such as bone, teeth, or hair.The reference index contains DNA profilesfrom related individuals of missing personsso that they can be periodically comparedto the unidentified persons index.All samples for this index are typed usingmtDNA and STR DNA analysis (if possible)to maximize the power of advancingtechnology.9

SPECIAL REPORT / JULY 02The offenderindex containsDNA profilesof individualsconvicted ofcertain crimes.The forensic indexcontains DNAprofiles obtainedfrom crimescene evidence.How does CODIS work?CODIS uses two indexes to generateinvestigative leads in crimes for which biologicalevidence is recovered from a crimescene. The convicted offender index containsDNA profiles of individuals convictedof certain crimes ranging from certainmisdemeanors to sexual assault and murder.Each State has different “qualifyingoffenses” for which persons convicted ofthem must submit a biological sample forinclusion in the DNA database. The forensicindex contains DNA profiles obtainedfrom crime scene evidence, such assemen, saliva, or blood. CODIS usescomputer software to automaticallysearch across these indexes for a potentialmatch.A match made between profiles in theforensic index can link crime scenes toeach other, possibly identifying serialoffenders. Based on these “forensic hits,”police in multiple jurisdictions or Statescan coordinate their respective investigationsand share leads they have developedindependent of each other. Matches madebetween the forensic and convictedoffender indexes can provide investigatorswith the identity of a suspect(s). It isimportant to note that if an “offender hit”is obtained, that information typically isused as probable cause to obtain a newDNA sample from that suspect so thematch can be confirmed by the crime laboratorybefore an arrest is made.LDIS, SDIS, and NDISCODIS is implemented as a distributeddatabase with three hierarchical levels (ortiers)—local, State, and national. All threelevels contain forensic and convictedoffender indexes and a population file(used to generate statistics). The hierarchicaldesign provides State and local laboratorieswith the flexibility to configureCODIS to meet their specific legislativeand technical needs.A description of the three CODIS tiersfollows (see exhibit 2).■ Local. Typically, the Local DNA IndexSystem (LDIS) installed at crime laboratoriesis operated by police departmentsor sheriffs’ offices. DNA profiles originatedat the local level can be transmittedto the State and national levels.■ State. Each State has a designated laboratorythat operates the State DNAIndex System (SDIS). SDIS allows locallaboratories within that State to compareDNA profiles. SDIS also is the communicationpath between the local andnational tiers. SDIS is typically operatedby the agency responsible for implementingand monitoring compliancewith the State’s convicted offenderstatute.■ National. The National DNA IndexSystem (NDIS) is the highest level ofthe CODIS hierarchy and enables qualifiedState laboratories that are activelyparticipating in CODIS to compareDNA profiles. NDIS is maintained bythe FBI under the authority of the DNAIdentification Act of 1994.Limitations of using theDNA databaseThe more data contained in the forensicand offender indexes of CODIS, the morepowerful a tool it becomes for lawenforcement, especially in its applicationto unsolved case investigation. However,because many jurisdictions are in theprocess of developing and populating theirDNA databases, convicted offender andforensic casework backlogs have beencreated over time and continue to growfor several reasons. First, as States recognizethe crime-solving potential of DNAdatabases, they continue to expandthe scope of their convicted offenderlegislation, which increases the number of10

USING DNA TO SOLVE COLD CASESExhibit 2. CODIS tierssamples to be collected and analyzed bythe DNA laboratory. As a result, more than1 million uncollected convicted offenderDNA profiles are “owed” to the system.An equally important but more difficultproblem to quantify is that of unprocessedcasework that contains biological evidence.This casework backlog may includenonsuspect or unsolved cases that couldbe analyzed and solved as a result ofadvancements in DNA technology.Convicted offender backlogsAlthough all 50 States have passed DNAdatabase legislation, many States havebacklogs of convicted offender samplesthat have been collected but have not yetbeen analyzed. Although Federal fundinghas played an important role in reducingexisting backlogs, the crimefighting potentialof DNA has prompted many States torevise their statutes to require nonviolentconvicted offenders to provide a DNAsample for analysis and upload intoCODIS. The trend toward expanding convictedoffender DNA statutes to includenonviolent offenders has significantlyincreased the number of DNA samplesrequiring collection and analysis. Althoughthe success of using the DNA database asa crime-solving and crime-prevention toolcan easily be demonstrated once convictedoffender backlogs are reduced, itshould be recognized that new backlogs11

SPECIAL REPORT / JULY 02are instantly created by the passage ofexpanded DNA legislation laws. Convictedoffender backlogs are an ongoing logisticalissue that can compound the complexityof investigating cold cases by using theDNA database.Forensic casework backlogsAddressing issues that affect the efficientand effective use of DNA databases in theUnited States is complicated further bythe existence of casework backlogs. Thisrefers to biological evidence in perhapstens of thousands of criminal cases,including violent and nonviolent crimes,that has not been tested or retested forDNA.Unprocessed rape kits are a clear exampleof this kind of backlog. Despite the establishedfact that rape typically yields biologicalevidence, as of October 1999, at least180,000 rape kits remained on shelvesacross the country, unprocessed, becauseno suspects have been identified. TheDNA evidence from these and other criminalcases often is not analyzed andentered into the DNA database becauseforensic laboratories have to prioritize theirwork and cases scheduled for trial takeprecedence over cases in which no suspectis known. In most jurisdictions, nonsuspectcriminal cases that containbiological evidence are not being analyzedand entered into the DNA database. Inmany jurisdictions, DNA from crimescenes is still primarily used to prosecuteoffenders, not to investigate crimes. Theconvicted offender backlog and limitedresources for casework going to trial precludeState forensic laboratories from analyzingall biological evidence for DNA,which in turn prevents law enforcementfrom being able to realize the full crimesolvingpotential of CODIS.The backlog of forensic cases has practicalconsequences for most law enforcementagencies in the United States. Laboratorycapacity limitations result in the ability toprocess crime scene samples from onlythe most serious of offenses. More andmore, however, agencies such as those inthe United Kingdom are discovering thevalue of DNA technology in solving propertycrimes. Blood left on a broken apartmentwindow or saliva found on adiscarded beer bottle can be used toidentify burglars, and the skin cells rubbedoff onto the steering wheel of a stolenvehicle can solve car thefts. However, aslong as forensic laboratories remain ableto process only the most serious cases,the full potential of DNA technology tosolve crime will remain untapped.12

Practical ConsiderationsLocal prosecutorscan providevaluable insightinto legal issues.Victim/witnessunits or advocatescan help locate,educate, andencouragewitnesses. Consultationwithrepresentativesfrom the crimelaboratory iscritical.A broad range of considerations must bemade long before any DNA testing is actuallyattempted in older, unsolved cases.These include—■ Legal considerations, such as the applicationor expiration of statutes of limitation.■ Technological considerations, such asthe nature and condition of the evidenceas originally collected, stored, and insome instances, subjected to otherforensic tests.■ Practical considerations, such as theavailability of witnesses in the eventDNA testing would identify a suspectand lead to an arrest and a trial.■ Resource issues, such as the time andmoney available for investigation andforensic analysis.The nature and scope of these issuesrequire that any approach to reexaminingold cases for potential DNA evidence becollaborative, whether by an individualinvestigator or by a specialized unit developedspecifically for cold case review.Local prosecutors can provide valuableinsight into legal issues that might preventor help a future prosecution. Victim/witnessunits or advocates can provide valuableassistance with locating, educating, andencouraging witnesses. Consultation withrepresentatives from the crime laboratoryis critical to ensuring that potential DNAevidence can be successfully analyzed.Evidence considerationsWhen collecting unsolved case evidencefrom storage facilities, the case investigatorshould be ready to handle all types ofpackaging disasters. Evidence may bestored in heavy-duty plastic bags, stapledshut as the past form of “sealing.”Multiple items may be sealed in one plasticbag, or even unpackaged in large,open, cardboard boxes. Unprotectedmicroscope slides from medical facilitiesmight also be found as a result of investigatingold cases. No attempt should bemade on the part of the investigator toseparate and repackage evidence. Thecondition and position that the evidencehas been stored in could provide valuableclues to the forensic scientist for testabilityof evidence. Only when evidence isfound unpackaged should the investigatorproperly package and label the item(s) tominimize the possibility for contaminationfrom that point forward. It is importantthat any evidence items are handled minimallyand only by individuals wearing disposablegloves. As always, it is also veryimportant that all actions taken as a resultof opening, evaluating, packaging, orrepackaging evidence are documentedthoroughly in the case folder.Degraded evidencePrior to the frequent use of DNA technology,biological evidence may have beencollected and stored in ways that were notnecessarily the best methods for preservingsamples for future DNA testing. Forexample, evidence containing biologicalfluids that were originally collected forABO Blood Typing analysis or other serologymethods may have been packaged orstored in ways that can limit DNA testing.Some methods of collection and storagemay promote the growth of bacteria andmold on the evidence. Bacteria can seriouslydamage or degrade DNA containedin biological material and inhibit the abilityto develop a DNA profile; however, evidencecan still sometimes yield DNAresults. For example, PCR technology canallow the laboratory to develop profiles13

SPECIAL REPORT / JULY 02from some moldy biological samples,whereas other evidence may fail to yield ausable DNA profile, even when no mold isvisible. Therefore, close consultation withthe laboratory is important to determinethe type of DNA testing most likely toyield results on the available evidence.Contamination issuesEVIDENCE HANDLING RECOMMENDATIONSBecause of the particularly sensitivenature of DNA technology, the potentialcontamination of evidence should be carefullyconsidered. Technologies used toanalyze evidence prior to the forensicapplication of DNA were not always sensitiveto contaminants. Evidence in oldercases may have been collected in waysthat lacked appropriate contamination orcross-contamination safeguards, whichcan make the DNA results less useful oreven misleading. In these cases, clarifyingresults by identifying the contributor of anadditional profile can determine whetherthe DNA results may now be used. Whena mixture is detected, a careful reconstructionof the evidence collection, storage,and analysis process must beundertaken. It may be determined thatDNA profiles will be required from onsceneofficers, evidence technicians, orlaboratory scientists who had access tothe evidence for comparison with evidenceresults. In these instances, properchain-of-custody reconstruction is critical.■ Wear gloves. Change them between handling each item of evidence.■ Use disposable instruments or clean instruments thoroughly before andafter handling each evidence sample.■ Avoid touching the area where you believe DNA may exist.■ Avoid touching your face, nose, and mouth when examining and repackagingevidence.■ Put dry evidence into new paper bags or envelopes; do not use plastic bags.■ Do not use staples.■ If repackaging of evidence is necessary, consult with laboratory personnel.It is also important to avoid contaminationwhen handling biological evidence duringthe course of the current review. If evidencethat may contain biological materialis already sealed, do not reopen it beforesending it to the laboratory. (See EvidenceHandling Recommendations.)Legal considerationsNumerous legal issues might arise whenexamining older cases for potential DNAevidence. These issues are most likelyjurisdictionally specific and may differ fromState to State. Although most jurisdictionsmaintain no statute of limitation for filingcharges in a homicide case, States canvary widely in the time allowed for filingcharges in other cases, such as rape andother sexual assault crimes. Furthermore,in recognition of DNA technology’s abilityto solve old cases, many States areextending or even eliminating statutesof limitation for certain crimes.Chain of custodyWhen a case remains unsolved for a longperiod of time, evidence is usually handledby an increased number of individuals.Many unsolved cases to be reviewed forDNA evidence may have been previouslyreinvestigated or handled by several differentinvestigators as a result of new leadsor periodic, systematic reviews. Furthermore,as cases age, the likelihood increasesthat evidence may be moved to new orremote storage locations as evidencefrom newer cases fills police departmentshelves.Many cases may also have had evidencesubmitted to the laboratory for variousforms of forensic testing. Evidence inolder cases may have been submitted forstandard serological testing, but can nowbe tested for DNA with much greater success.Hair previously submitted for standardmicroscopic hair analysis may now14

USING DNA TO SOLVE COLD CASESbe submitted for mtDNA testing. As withall criminal investigations, chain-of-custodyissues are critical to maintaining theintegrity of the evidence. In all cases, theultimate ability to use DNA evidence willdepend on the ability to prove that thechain of custody was maintained.Statutes of limitationOne of the first issues to address whenreviewing an unsolved case is whetherthe statutes of limitation on a case haverun out. Several considerations arise whenaddressing a statute of limitation issue.Good communication between law enforcementand local prosecutors is criticalwhen examining these legal questions.Changes in statutes. Advances in DNAtechnology and the creation of DNA databasesare leading many criminal justiceprofessionals to rethink time limits placedon the filing of criminal charges. Becausebiological evidence can yield reliable DNAanalysis results years after the commissionof a crime, many State legislatureshave begun to extend, and in somecases eliminate, the statutes of limitationfor some crimes and in certain circumstances.Many States have extended thelength of time for which a complaint canbe filed, other States have eliminatedstatutes of limitation for certain crimes,and some legislation is retroactive.Exceptions to statutes. Exceptions oftenexist under existing and new statutes.Under such exceptions, time can beadded to the statute of limitation, givingpolice the legal authority to arrest even ifit appears as though the statute has runout. For example, many jurisdictions haveexceptions for a suspect’s flight from jurisdiction.In a case for which there is a5-year statute of limitation, if the governmentcan prove that the suspect has beenabsent from the jurisdiction for 2 years,the State can still file against the suspectfor up to 7 years after the commission ofthe crime. Exceptions also exist for casesin which child victims are assaulted by afamily member, which can be valuable inthe context of a current investigation.Victim and witnessconsiderationsAnother important consideration to bemade early in the process is the willingnessof victims and witnesses to proceed.Although many victims may continuouslymonitor the progress of their investigations,some choose to detach from theprocess over time. Reinvestigating a casemay cause renewed psychological traumato the victim and victim’s family. It shouldnot be assumed that victims and witnesses,even if they were eager to pursue thecase when it occurred, are still interestedin pursuing the case. A phone call from aninvestigator years later may not be a welcomeevent. Whenever possible, enlistthe aid of victim service providers. If anew officer is handling the investigation,enlisting the assistance of the originalinvestigator to make the first contact withthe victim may also be helpful.The older a case is, the more difficult itmay be to locate witnesses. However,early identification of victim and witnessavailability may ultimately save significantresources. Consultation with prosecutorsis mandatory when considering whether awitness would be necessary at trial.STATUTE OF LIMITATION RECOMMENDATIONS■ Know the original statute of limitation.■ Determine whether the law has changed regarding time limits for filing.If so, is the law retroactive?■ Determine whether there are exceptions to the statute.■ Consult with the prosecutor.It should not beassumed thatvictims and witnessesare stillinterested in pursuingthe case.Whenever possible,enlist theaid of victimservice providers.15

Identifying, Analyzing, andPrioritizing CasesGoodcommunicationbetween police,laboratories, andprosecutors canhelp identify andconvict seriousoffenders and savevaluable timeand resources.Whether the process of reviewingunsolved cases is initiated by a single officeror by a specialized unit, it must ultimatelybe a team effort. At all stages ofthe process, investigators should availthemselves of the scientific advice of thelaboratory and the legal expertise of thelocal prosecutor’s office. Close consultationwith the laboratory can ensure thatevidence integrity is maintained and thatlimited laboratory resources are allocatedeffectively. Similarly, prosecutors can helpidentify issues that might occur at trial if asuspect is identified and arrested uponsuccessful DNA testing. Good communicationbetween police, laboratories, andprosecutors can help identify and convictserious offenders and save valuable timeand resources.Identify potential casesfor reviewAn initial step in the DNA review ofunsolved cases is to identify cases thatmight be amenable to DNA testing. Whilethe cases considered for this kind ofreview will vary from jurisdiction to jurisdiction,it is important to define minimumrequirements that will likely benefit fromthis approach. Issues such as statutes oflimitation and solvability factors should bethoroughly examined in cooperation with aprosecutor and the forensic laboratory toestablish guidelines for case selection. Italso will be important to identify the ultimategoals of the program so that theselection criteria can be tailored to meetthose specific goals.Cases that could benefit from a reviewfor potential DNA evidence can be identifiedfrom numerous sources. In someinstances a single police officer or investigatormay remember an unsolved casefrom years ago. In some departments aformalized cold-case unit may systematicallyreview cases for the potential of DNAtesting. Other cases may be identified bycoordinated, interdepartmental efforts, victimsor witnesses who have heard aboutthe potential of DNA evidence, and laboratoriestaking inventory of their storagefacilities. If a department is pursuing a systematicreview of cases, either by one ortwo officers or by a formal unit, there aremany sources that can be consulted forvaluable investigative information, suchas—■ Autopsy, laboratory, prosecutor, andlocal agency logbooks.■ Retired investigators.■ Computer databases.Identify statute oflimitation issuesStatute of limitation issues might affectthe ultimate ability to prosecute a case.Cases should be preliminarily reviewed byinvestigators in conjunction with the prosecutor’soffice to identify which prosecutionswould be barred by the statutes oflimitation. If the goal of the unsolved casereview program is to obtain convictionsand statutes of limitation have expired ona particular case, a department may wishto save its resources for cases likely toyield convictions. However, if the goalof the program is to solve and close unsolvedcases regardless of whether a convictioncould be obtained, a jurisdictionmay decide to review all cases that qualifyunder its guidelines. This is an importantconsideration in the context of investigatingserial offenders whose criminal actsmight span the course of years ordecades.17

SPECIAL REPORT / JULY 02Define categories of cases—solvability factorsBecause the number of cases that qualifyfor reinvestigation might be very large, itmay be beneficial for a jurisdiction todefine cases according to several solvabilityfactors. Solvability factors include factsand circumstances of a case that influencethe likelihood that it might be solvedthrough advancements in DNA technology.For example, a high probability existsthat analysis of nonsuspect rape kits willyield valuable DNA results. Profiles generatedas a result of DNA analysis can nowbe entered into CODIS, which can solve acase by matching to a convicted offender,or aid investigations by linking serial rapesto each other. Additionally, if an unsolvedmurder case contains biological evidenceforeign to the victim that did not produceviable results from ABO blood typing orRFLP DNA analysis, evidence could bereanalyzed with the more discriminatingand powerful STR technology. It is alsoimportant to recognize and sort out casesthat might not be as likely to be solvedwith DNA technology. An example mightbe an unsolved drive-by homicide becausethe perpetrator most likely would not haveleft biological evidence at this kind ofcrime scene.Case review—establish prioritiesOnce solvability factors and statute of limitationissues are addressed, it is importantto continue the process by identifying thecases to be reviewed first. To preserveinvestigative resources when consideringa larger number of unsolved cases forreview, jurisdictions may prioritize accordingto the likelihood that cases will besolved or the likelihood that investigationswill be aided. In establishing this priority,the following criteria can be considered:■ How many qualifying cases are there?■ Where are the case files located?■ Are case summaries available?■ How many cases will be assigned toan investigator?To establish an investigative hierarchy,qualifying cases should be reviewed byexperienced, proficient investigators. Achecklist can be used throughout thereview process so that managers candecide which cases will be worked first.A checklist can also provide review processconsistency throughout the agency.(See Sample Checklist at the end of thisreport.) The following categories mayserve as a model for a hierarchy in prioritizingcases:■ There is a known suspect and physicalevidence appears to have been preservedin a manner consistent with successfulDNA testing and use of CODIS.■ There is no known suspect but physicalevidence has been preserved in a mannerconsistent with successful DNAtesting and use of CODIS.■ There is no known suspect and evidencewas collected and preserved ina manner that may make it difficult toobtain a DNA profile.Locating case files,obtaining evidence logs,and other documentationLocating the case file and original evidencefor the investigation may be a challengingendeavor. Changes in personnel, procedure,and facilities and the passage oftime may complicate the process. Whensearching for a case file or evidence, aninvestigator may need to look in numerous18

USING DNA TO SOLVE COLD CASESplaces. Potential locations include, but arenot limited to, the following:■ Police department property rooms (casefiles, evidence logs, whole evidence).■ Property warehouses (case files, evidencelogs, whole evidence).■ Public crime laboratories (previouslytested/submitted evidence, lab reports).■ Private laboratories (previously testedevidence, lab reports).■ Hospital/medical facilities (rape kits,medical reports, slides).■ Coroner/medical examiners’ offices(autopsy reports).■ Courthouse property rooms.■ Prosecutors’ offices (previous trial orsuspect investigation).■ Retired investigators’ files (case notesand details not contained in file).■ Other investigating agency offices(investigative leads—serial offender).Forensic testing reports andpreviously tested evidenceBecause advancements in DNA technologyenable laboratories to successfully analyzeold evidence that might have beenimproperly stored or subjected to previousforensic analysis, it will be very valuable tolocate any and all forensic reports thatwere produced as a result of previousanalysis and/or testing. ABO blood typing,microscopic hair analysis, RFLP DNAanalysis, or fingerprint analysis (amongothers) might have been performed in thecourse of the original investigation. Theoriginal case file should indicate whetherand which types of forensic analysis wereattempted. These reports also serve tomemorialize proper chain of custody.Cooperation with the crime laboratory iscrucial to locate and interpret existingforensic reports and to determine whetherevidence would be amenable to reanalysiswith new DNA techniques.Many combinations of options are availableto investigators and laboratory personnelif biological evidence was availableand previously tested. Exhibit 3 may serveto help investigators as they work with thelaboratory to discuss options throughoutthe course of the investigation.Locate biological evidenceWhen reviewing the case file for potentialDNA evidence, it is important to knowwhat kinds of evidence may yield a DNAprofile. Given the power and sensitivity ofnewer DNA testing techniques, DNA canbe collected from virtually anywhere. Onlya few cells can be sufficient to obtain usefulDNA information to help solve a case.Exhibit 4 identifies some common items ofevidence that may have been collected previouslybut not analyzed for the presenceof DNA evidence. Remember, if a stain isnot visible it does not mean that there arenot enough cells for DNA typing. Further,DNA does more than just identify thesource of the sample; it can place a knownindividual at a crime scene, in a home, or ina room where the suspect claimed not tohave been. It can refute a claim of selfdefenseand put a weapon in the suspect’sDNA CAN DO MORE . . .. . . than identify a suspect. It can also—■ Place a known individual at a crime scene.■ Refute a claim of self-defense.■ Put a weapon in a suspect’s hand.■ Change a suspect’s story from an alibi to one of consent.19

USING DNA TO SOLVE COLD CASESsuch as serological testing, was performedduring the course of the originalinvestigation.Additionally, elimination samples from anyonewho had lawful access to the crimescene, such as family members, may berequired if the laboratory determines thatthere is more than one DNA profile presentin the evidence sample. Early identificationof the location and status ofpersons who might be requested to submitan elimination sample could save valuabletime and resources if the laboratoryneeds such information. Consultation withthe laboratory is essential to properly coordinatingthis process.Follow agency proceduresfor submitting the DNAprofile to CODISOn successful laboratory analysis resultingin a DNA profile developed from crimescene evidence, existing and/or new suspectDNA profiles should be comparedwith the evidence profile. If the laboratorydetermines a match between a suspectand the evidence, the prosecutor’s officeshould be consulted on how to proceed.However, if a match is not found, agencyprocedures should be followed, in accordancewith the crime laboratory, to submitthe crime scene evidence DNA profile intoCODIS.Exhibit 4. Common items of evidenceEvidence Possible location of DNA on the evidence Source of DNABaseball bat Handle Skin cells, sweat, blood, tissueHat, bandanna, or mask Inside surfaces Sweat, hair, skin cells, dandruff, salivaEyeglasses Nose or ear piece, lens Sweat, skin cellsFacial tissue, cotton swab Surface Mucus, blood, sweat, semen, ear waxDirty laundry Surface Blood, sweat, semen, salivaToothpick Surface SalivaUsed cigarette Cigarette butt (filter area) SalivaUsed stamp/envelope seal Moistened area SalivaTape or ligature Inside or outside surface Skin cells, sweat, salivaBottle, can, or glass Mouthpiece, rim, outer surface Saliva, sweat, skin cellsUsed condom Inside/outside surface Semen, vaginal or rectal cellsBed linens Surface Sweat, hair, semen, saliva, blood“Through and through” bullet Outside surface Blood, tissueBite mark Surface of skin SalivaFingernail/partial fingernail Scrapings Blood, sweat, tissue, skin cellsNote: When reviewing evidence, it is important to maintain chain of custody, consult with laboratory personnel, and take all appropriate precautions against contamination,including wearing gloves and changing them between handling of different pieces of evidence.21

SPECIAL REPORT / JULY 02Because CODIS contains hundreds ofthousands of convicted offender DNA profiles,it is possible that the person whocommitted the unsolved crime beinginvestigated was convicted of a qualifyingoffense that required submission of aDNA profile to the database. If that personhas not previously been convicted of aqualifying offense, especially in light ofexpanding database law, it is possible thatthey will be convicted in the future.Further, because the forensic index ofCODIS contains thousands of crime sceneevidence profiles, the investigation couldbe aided if a match is made to anotherforensic DNA profile already in the database.Finally, an investigator should notassume that a new DNA profile generatedfrom unsolved case evidence and submittedto the laboratory for entry into CODISwill be compared with every possible convictedoffender or crime scene index profile.The investigator may need toproactively request that his CODIS administratorsearch the new profile against thelocal, State, and national DNA databases.Prepare a John Doe warrantCODIS is a powerful crime-solving andcrime-prevention tool, but many cases willnot be solved as a result of entering aDNA profile into the forensic index of thedatabase. Additionally, many cases willhave statute of limitation issues that mightprevent the prosecution of the case if amatch is not determined in a timely manner.Therefore, if no offender matchoccurs in cases in which statutes of limitationare an issue, consideration may begiven, in consultation with the prosecutor,to preparing a John Doe warrant. Thesetypes of warrants can identify the perpetratoraccording to his or her DNA profile.The 13-loci profile generated by the crimelaboratory should be clearly printed on theface of the warrant. The John Doe warrantis not novel; however, the unconventionalmethod of describing an individual by hisor her DNA profile may allow for prosecutionof a case if a DNA match isdetermined in the course of future investigationsor as a result of the CODIS systembeing populated with more convictedoffender and forensic DNA profiles.Notes1. CODIS uses two indexes—the forensic index andthe offender index—to generate investigative leadsin crimes where biological evidence is recoveredfrom crime scenes. The forensic index contains DNAprofiles of biological crime scene evidence and theoffender index contains DNA profiles of individualsconvicted of a qualifying offense.2. CODIS has a missing persons index that exclusivelycontains mtDNA profiles; the convicted offenderand forensic indexes of CODIS exclusively containSTR DNA profiles.22

USING DNA TO SOLVE COLD CASESSAMPLE CHECKLIST■ Identify potential cases.■ Identify any statute of limitation issues (consult with prosecutors).■ Define case categories according to solvability factors.■ Prioritize cases (consider solvability factors).■ Locate and review the case file; obtain evidence logs and other documentationsuch as laboratory and autopsy reports.■ Locate previous forensic testing reports and location of previously tested evidence.For example—■ Blood previously ABO typed.■ Hair analyzed microscopically.■ Fingerprint evidence.■ Locate crime scene evidence containing biological material.■ Evaluate the case and evidence for potential probative DNA. Be sure to—■ Consider all evidentiary possibilities.■ Take appropriate precautions against contamination.■ In consultation with the laboratory and prosecutors, submit appropriate (probative)evidence to the laboratory for testing.■ Continue investigative protocol. If needed, obtain reference samples from suspects—■ Voluntarily using a consent form.■ By using a previously obtained sample (e.g., if a reference sample was usedfor standard serological testing).■ Identify witness issues—■ Legal availability.■ Willingness to proceed.■ Location.■ If a profile does not match suspect profiles, follow agency procedures for submitting theevidence profile to CODIS.■ If no offender match occurs in cases in which statutes of limitation are an issue, preparea John Doe warrant.23