When police are investigating an alleged crime, one of the most important tools that they have is deoxyribonucleic acid—commonly known as DNA. This is a relatively new type of evidence, and it’s being used more often all of the time. What makes it so important to these investigations?
There are a few reasons for the importance, but it all starts with the fact that DNA is truly unique. Two people never have the same DNA; it’s even easier to determine whether there is a match than by using fingerprints. This means that DNA evidence can be strongly linked and is not thought to bring about false positives.
There is only one exception to this rule, and that’s in cases of identical twins, who do have the same DNA.
Another thing that makes DNA so important is that there is more than one way to find it. For example, if there is any blood at the crime scene, the police can use it to examine the DNA. The same goes for a single piece of hair. Both skin cells and semen also contain DNA. On the whole, this means DNA can be found at many different types of crime scenes.
For those who are accused, DNA is also important, as it has been used to clear people who are innocent and who have been convicted based on other evidence. Even when video evidence suggests a person was at the crime scene and the jury thinks there is a motive, DNA evidence can prove indisputably that someone else was there—even if it’s not yet known who that was.
For those accused of sex crimes in Pennsylvania, it’s crucial to understand the way DNA evidence can be used, how it can be obtained, and what it means for the case.
Source: National Institute of Justice, “Understanding DNA Evidence: A Guide for Victim Service Providers,” accessed Oct. 20, 2015