DNA was a breakthrough when law enforcement first began using it to identify suspects. The technology has also increased and improved by leaps and bounds. However, despite its high-tech nature, DNA is not infallible.
The US Department of Justice explains human error can lead to corruption of DNA evidence that completely changes its value.
When collecting DNA, there must be a careful process to avoid contamination. Mixing samples up or not properly labeling samples can ruin the evidence and make it unusable. Getting other biological matter in samples is also a concern, or allowing other particles into a sample will void it. These things can happen easily and even without awareness, but they jeopardize the DNA sample.
If the samples do not have proper labels, it is highly possible they could become lost or end up in with samples from another case. They could also become compromised due to issues with the containers that allow in moisture and dust particles. Even the packaging itself can introduce containments.
Processing errors in the lab can happen for a number of reasons. A tech may lack proper training or have a messy work area that leads to contamination. The lab might ruin a sample or run into issues with equipment that causes problems. There is a lot of room for human error in a lab setting, especially if those working with samples do not know proper procedures.
DNA evidence can be an amazing tool for prosecutors, but if there is any possibility of contamination, it makes it void. Unfortunately, there is a lot of potential ways contamination can occur during the process from scene to submission in court, from simple mistakes to major issues.