Investigating CSI – Background material Table of Contents I ...
Investigating CSI – Background material Table of Contents I ...
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<br />
cells that can be pr<strong>of</strong>iled.<br />
Sifting through scenes <strong>of</strong> crime for possible sources <strong>of</strong> evidence requires lateral<br />
thinking and nothing can be discarded in case it develops significance later in a<br />
police investigation. DNA testing now uses the quicker method <strong>of</strong> pr<strong>of</strong>ile numbers<br />
rather than 'barcodes'.<br />
In sexual <strong>of</strong>fences acid phosphate tests are used to identify semen. However, the<br />
department also investigates the damage <strong>of</strong> underwear to determine whether the<br />
damage is recent or self-inflicted. The ends <strong>of</strong> fibres can tell whether the<br />
underwear is torn, cut or just very old. This type <strong>of</strong> investigation is obviously<br />
important in rape cases.<br />
Analysis <strong>of</strong> hairs and clothes fibres is another way <strong>of</strong> gathering evidence<br />
although the success <strong>of</strong> DNA has meant that hair analysis is now rarely used.<br />
Fibres can provide excellent pro<strong>of</strong> <strong>of</strong> recent contact and can be used to back up<br />
DNA evidence. Lateral thinking is needed in looking for samples - for example<br />
how someone would have escaped from a crime and thus possibly left samples<br />
while climbing a wall.<br />
Forensic biologists also attend scenes <strong>of</strong> crime which can cover very large areas<br />
- especially if streets have to be closed down. Forensic biologist can find<br />
themselves in difficult working conditions - freezing cold fields in the middle <strong>of</strong> the<br />
night or derelict buildings. Marie pointed out that TV programmes on forensic<br />
examinations where sharp suited detectives wandered through the crime scene<br />
instantly deciphering clues were far removed from reality. Scenes <strong>of</strong> crime were<br />
now overseen by managers who ensure that the sites are secure to preserve<br />
evidnece. Forensic scientists dress in all over white suits to avoid not only<br />
contaminating evidence but also the evidence contaminating workers.<br />
The National DNA Database was established in 1995 and holds DNA pr<strong>of</strong>iles<br />
from mouth swabs (Criminal Justice samples - CJ)) <strong>of</strong> convicted criminals and<br />
records <strong>of</strong> outstanding crimes. The database is run by the Forensic Science<br />
Service in Birmingham although there are also local facilities at Dundee. The<br />
database currently holds around two million CJ samples and 160,000 crime<br />
scene pr<strong>of</strong>iles. Obviously the use <strong>of</strong> the database to solve crime can only<br />
succeed if a suspect has committed a previous crime but since 1995 a large<br />
amount <strong>of</strong> violent crime has been solved by running crime scene pr<strong>of</strong>iles against<br />
CJ samples - including 1,000 murders and 1,800 rapes. Cases from the past<br />
have been solved as the same person commits new crimes or new CJs are<br />
logged on the database.<br />
The lecture was followed by a question and answer session that included a<br />
number <strong>of</strong> points including the necessary qualifications to enter a career as a<br />
forensic scientist, recruitment and retention and quality audits.<br />
4