INTERPOL HANDBOOK ON DNA DATA EXCHANGE AND PRACTICE

•basic elements of a dna reportDifferent laboratories vary the format of their DNA reports, however quality controlstandards dictate that the laboratory report must include statements that address thefollowing basic elements:• Description of all items received and their packaging, labelling and personal transferof custody of the exhibits from the investigator to the laboratory, and summary ofthe established chain of custody• Description of evidence examined• Methodology used for examination• Scientific screening of items and the testing of Short Tandem Repeat loci (STRs)and an explanation of Polymerase Chain Reaction (PCR).• DNA Results• The STR loci examined and the alleles detected are normally listed as a seriesof numbers representing the different forms of DNA (alleles) detected.The profiles themselves may or may not be reported in the laboratory reportbut the outcomes and conclusions from the testing will always be reported.• If the quality is sufficient, the profiles will be forwarded to the DNA Database.This will often not be possible when mixed stains or very low amounts of stainsare detected. These samples can often be used for a direct comparison at a laterstage when a suspect is found.• Interpretation of results inconclusive• An inconclusive - DNA report in which the suspect is neither excluded norincluded can occur due to insufficient DNA being present in the exhibits or thepoor quality of the evidence. Inconclusive results also can occur if the evidentiarymaterial contains a mixture of DNA from several individuals, for example a rapecase involving multiple assailants, which prohibits interpretation.• No DNA or Insufficient DNA - The absence of DNA from the evidence maybe because there is no DNA deposited (such as the use of a condom during arape), insufficient DNA present in the exhibit, the DNA is degraded, or due tothe presence of factors that inhibit the PCR amplification and subsequent analysisof the DNA. A negative result is not equivalent to an exclusion result, as it onlymeans that DNA was not detected in the exhibit tested.• Statement on the Deposition of Evidence• The evidence is packaged and returned to the submitting agency or it may havebeen consumed during the analysis.INTERPRETATION OF THE DNA PROFILE PAGE 33