Even though there are plenty of people in jails and prisons in the U.S., it is not necessarily easy for prosecutors to secure convictions. Before even bringing criminal charges against a defendant, most prosecutors have to be certain they have compelling evidence. This is because they must prove each element of a criminal offense beyond a reasonable doubt.
To do so, prosecutors introduce evidence. While jurors are generally free to give whatever weight they want to evidence, some evidence is more convincing than others. Simply put, DNA evidence is often hard for jurors to ignore.
The nature of DNA evidence
Human beings are complex organisms, with each individual having unique strains of deoxyribonucleic acid. This DNA is present in everything from blood to hair follicles. As you might suspect, it is possible to leave DNA evidence at a crime scene, especially if a person bleeds there.
Touch DNA can contaminate any crime scene
Modern science gives crime scene investigators many different ways to collect DNA evidence. While past investigators needed large samples, today’s investigators can get by with substantially less. Indeed, they might uncover touch DNA at a crime scene. According to a recent research published in Forensic Science International: Synergy, touch DNA is DNA a person transfers to a surface simply by touching or rubbing against it.
Defendants have some options
Even though prosecutors might have DNA evidence that links a suspect to a crime, defendants do not have to idly accept the evidence. Diligent defendants typically file requests to test and analyze data. They also investigate how crime scene investigators obtained DNA evidence and look into its chain of custody.
Ultimately, if prosecutors intend to introduce DNA evidence at trial, defendants must be sure they fully examine the evidence for any possible discrepancies or problems.