Forensics, or forensic science as it should be known, is the detailed examination of evidence discovered at a crime scene, for use in a court of law.

Forensic DNA testing specifically relates to using unique DNA marker information to tie an individual to a crime or scene, in much the same way that fingerprinting has done in the last century or so.

The advantages of using DNA testing are that DNA can be left in many places that fingerprints cannot, i.e. in sex crime cases.

The downside is that forensic DNA testing can prove expensive. In the above types of case the cost can easily be a few hundreds of pounds and upwards.

In murder cases the costs rise sharply, often into the thousands.

Obviously, fingerprinting as a means of identification is much swifter and cheaper. Therefore, forensic DNA testing tends to be reserved for the more complex cases.

Complex

Forensic DNA testing is much more complex than standard DNA testing as the samples being examined are often from crime scenes rather than those taken from a living host. As such, there is a high probability they have become degraded and therefore of limited or restricted use.

However, where good quality DNA information is obtained, it is invaluable - courts quite readily accept forensic DNA evidence as the chances of misidentification are next to none when it has been examined under the correct protocols.

CODIS

In 1992 the FBI in America launched CODIS - the Combined DNA Indexing System - a tool that is widely referenced in today’s popular forensic television programmes.

CODIS is a central database that contains DNA information from criminals from across all the States of America.

The value of this is that many offenders go on to repeat their crimes. Therefore, data from crime scenes can quickly be matched with CODIS in order to identify known criminals with ease.

Forensic DNA testing has revolutionised criminology in much the same way that fingerprinting did when it first became widely used.

Unsolved Cases

DNA information from unsolved crimes is retained and referenced as new DNA samples are taken from the populace in an attempt to close old cases.

Suspects have been convicted or acquitted based purely on forensic DNA in areas where there may have previously been an element of doubt as to their guilt or innocence.

Forensic DNA has even been applied retroactively to famous old cases where there has been public interest.

There have been examples of executed prisoners being exhumed for testing in order to either prove their guilt once and for all, or to open their way for a posthumous pardon.