DNA analysis was first introduced to the U.S. courts in the early 1990’s. It is without a doubt the biggest advancement in Forensic Science since the discovery of fingerprints.
Why is DNA analysis so important in criminal investigations?
- A DNA profile can positively include or exclude a person as source of evidence.
- DNA results can be obtained from a very small, old or degraded sample, and is found in almost all biological material.
- With the exception of identical twins, no two people have the same DNA. It is unique.
What are the disadvantages of DNA analysis?
- Cost. DNA equipment and trained personnel are not cheap, although advances in science and technology are making it more affordable every day.
- Sensitivity. Because DNA is so prevalent and the techniques so sensitive, extreme care must be taken not to contaminate the evidence.
- Complexity. While the interpretation of a single source of DNA is usually fairly straight forward, it can be very difficult to correctly interpret samples with multiple sources and concentrations. Forensic scientist must undergo a long, continual training program to stay current with the technology.
- Time. Because of the complexity, DNA analysis usually takes several days at best. Also due to the demand, there is often a backlog of cases to be analyzed and a limited number of resources.
What types of tissue can be analyzed for DNA? There are many, but the most common are:
- Hair (with a root)
- Vaginal secretions
What types of evidence have been used for DNA analysis?
- Beverage containers
- Cheek swabs
- Sexual assault stains
- Chewing gum
Almost anything that comes in contact with the human body will contain traces of DNA and is a potential source of evidence.