Investigating CSI – Background material Table of Contents I ...

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DNA information. DNA testing can also be done on weapons - knifes collect skin cells that can be profiled. Sifting through scenes of crime for possible sources of evidence requires lateral thinking and nothing can be discarded in case it develops significance later in a police investigation. DNA testing now uses the quicker method of profile numbers rather than 'barcodes'. In sexual offences acid phosphate tests are used to identify semen. However, the department also investigates the damage of underwear to determine whether the damage is recent or self-inflicted. The ends of fibres can tell whether the underwear is torn, cut or just very old. This type of investigation is obviously important in rape cases. Analysis of hairs and clothes fibres is another way of gathering evidence although the success of DNA has meant that hair analysis is now rarely used. Fibres can provide excellent proof of recent contact and can be used to back up DNA evidence. Lateral thinking is needed in looking for samples - for example how someone would have escaped from a crime and thus possibly left samples while climbing a wall. Forensic biologists also attend scenes of crime which can cover very large areas - especially if streets have to be closed down. Forensic biologist can find themselves in difficult working conditions - freezing cold fields in the middle of the night or derelict buildings. Marie pointed out that TV programmes on forensic examinations where sharp suited detectives wandered through the crime scene instantly deciphering clues were far removed from reality. Scenes of crime were now overseen by managers who ensure that the sites are secure to preserve evidnece. Forensic scientists dress in all over white suits to avoid not only contaminating evidence but also the evidence contaminating workers. The National DNA Database was established in 1995 and holds DNA profiles from mouth swabs (Criminal Justice samples - CJ)) of convicted criminals and records of outstanding crimes. The database is run by the Forensic Science Service in Birmingham although there are also local facilities at Dundee. The database currently holds around two million CJ samples and 160,000 crime scene profiles. Obviously the use of the database to solve crime can only succeed if a suspect has committed a previous crime but since 1995 a large amount of violent crime has been solved by running crime scene profiles against CJ samples - including 1,000 murders and 1,800 rapes. Cases from the past have been solved as the same person commits new crimes or new CJs are logged on the database. The lecture was followed by a question and answer session that included a number of points including the necessary qualifications to enter a career as a forensic scientist, recruitment and retention and quality audits. 4
A forensic scientists needs a honours degree in biology and chemistry and a masters degree in forensic science to enter the profession. An forensic assistant will need an aapropriate HND or more. The high media profile of the work of a forensic scientist means that retention is more of a problem than recruitment. Marie Campbell believes that many come into the job believing it to be the kind of glamorous career profiled in television crime dramas and can be quickly disillusioned by the reality. While there was immense personal satisfaction it can be a hard job that should be considered as a vocation that someone would really want to enter as a career. Marie highlighted the obvious unpleasantness of attending a particularly nasty scene of crime or accident. There was also the added stress of being cross-examined in court even though that was something a scientist quickly becomes accustomed to. Was television giving the game away on how forensics can solve crime? Most crimes are committed out of rage, passion or are alcohol fuelled - whatever the motives few crimes are committed in such a rational, calm and 'intelligent' manner that would enable criminal to think and cover their tracks. Many suspects also tripped themselves up by insisting on versions of stories that conflicted with the facts uncovered by forensic investigation. The forensic laboratory with Strathclyde police is externally accredited and also undergoes internal audit once every two to three months. Chain of custody procedures with regard to transferring evidence from the laboratory to court are also rigorously The lecture was a fascinating insight into the work of a forensic scientist with illuminating examples of local and national cases where forensic investigation had helped to solve crime. Source: http://www.ibms.org/index.cfm?method=science.general_science&subpage=general_forensic_scientists 5
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Page 9 and 10: of unidentified remains with the pr
Page 11 and 12: Matching DNA Proving that a suspect
Page 13 and 14: Creating a DNA Profile: The Basics
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Page 17 and 18: power is the combined analysis of a
Page 19 and 20: of DNA profile comparisons done by
Page 21 and 22: II. Tools and Techniques for DNA Fo
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The Federal Bureau of Investigation
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III. Interesting Cases Using DNA Ev
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