DNA analysis of a single hair found in a victim's throat provided a critical piece of evidence in a capital murder conviction. (What Every Law) .
It was only until recently that scientists have been able to get DNA from things like hair, teeth and fingernails. DNA was generally found only in cells that have a nucleus, like blood and saliva. But scientists have been able to find that cells like fingernails and hair have something called mitochondrial DNA, a more primitive form of genetic coding inherited from the mother only. Crime fighters have adopted a mitochondrial DNA sequencing technique used by anthropologists to trace human ancestors. This procedure may not be as precise as the traditional DNA profiling but it is still a reliable source. (Kluger et al.).
The collection of DNA evidence often involves collecting very small samples and contamination can become an issue. The most common kind of DNA contamination comes when an officer is collecting and transporting a sample and gets some DNA from another source, most likely his own, mixed in with the sample. (What Every Law) New technology is making DNA contamination almost a non-issue. Cops will soon be able to analyze DNA within minutes, right at the scene of the crime. Nanogen, a San Diego biotech company has invented a postage-stamp sized chip that is designed to perform DNA analysis of drops of saliva, semen, hair, or other left behind remnants. A portable computer can them search the FBI's databases for a match. (Beiser) This procedure will not only reduce the risk of contamination, but it will also cut the time for DNA testing from weeks to minutes. This dramatic cut in time will also cut the price of DNA testing down to a fraction of what it currently costs. (Beiser) This new technology will make DNA testing much cheaper, and even more efficient. .
Since the early 1990's 116 people have been exonerated of crimes that they didn't commit because of post-conviction DNA testing.