How testing for DNA matches are performed
Scientists will test bone, body tissue, body products such as saliva, blood, and hair, to identify the DNA present in any individual. It is quite interesting to note that only one-tenth of a percent of DNA will differ among individuals. When we go back to our crime scene evidence, scientists must match the DNA evidence found at the scene with the suspect.
Forensic scientists use specific genetic markers.
Forensic scientists take small pieces of DNA information they have gathered called probes to see if this DNA sampling matches (binds) to the complementary DNA sampling that they have. A series of these probes that match forms a distinctive pattern and then that pattern is compared to the DNA sample of the suspect or the individual in question. Again, one marker is not enough, there would have to be about 5 markers that match to identify the suspect. Of course more markers would be even better, but it is very time consuming and very expensive and is not demanded in all court cases that much because of these factors.
At this point the chances are very good that the suspect was present at the scene of the crime. Note that DNA testing is not 100 percent accurate and there is a very slim chance, but a chance nevertheless, that someone else could have the same DNA profile for the probe or genetic marker sets.
The courts then decide how accurate the DNA evidence is. It may at that point ask for the full 13 loci to be conducted.
Even if only 5 loci are considered because that is all the evidence available (crime scene investigation is a piecemeal procedure and does not afford the DNA testing available for paternity testing), crime scene DNA is far superior to any evidence we have at present, including eyewitness accounts which are only 50 percent accurate.
DNA chip technology may soon be on the horizon to make stronger more accurate matches.
To be continued
Pro-ADN Diagnostic is Montreal’s Major DNA Testing Center www.proadn.com/
3885 Industriel Blvd.
Laval, QC H7L 4S3
T: (450) 663-6724 ext. 247
F: (450) 663-4428