Forensic DNA Evidence
The science of identifying individuals using DNA sequences is very clear, and the probability of scientific error is extremely small. As a result, DNA evidence has been used to help identify perpetrators of crimes and to exonerate innocent people before they become suspects.
The value of the evidence depends on the quality of the DNA samples and how well law enforcement agencies handle them. Most legal disputes over DNA evidence challenge the handling and storage of DNA samples.
Sources of DNA Evidence
DNA can be left behind in a surprising variety of forms, including saliva, blood, semen, skin, hair, tears, and more. As a result, crime scene evidence can often be traced to a specific individual even if there were no eyewitnesses, and DNA tests provide a more powerful tool than fingerprint analyses.
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DNA Evidence Is Left Behind In A Variety Of Forms
A skin cell, blood, and the shaft of a hair (shown from left to right) all contain DNA and can be collected as crime scene evidence. (Microscopic images of the skin cell and hair shaft courtesy of Joseph A. Brzostowski) |
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