DNA: How people are wrongfully convicted.
DNA profiling has been used in criminal cases for around 30 years, of which DNA has increasingly become one of the most reliable evidence mechanisms, as DNA is specific to each person; it can place a person at a crime scene much more reliably than footprints and other types of evidence. However, with any evidence there is often large amounts of uncertainty as it is hard to place exactly how a certain piece of evidence is relevant to the crime in question.
DNA has been vastly accepted by forensic professionals, as it is one of the only concrete ways to place a person at the crime scene, however with limited regulations in its early adoption this led the way for many to be wrongly incriminated due to flaws in testing.
As humans, we all share 99% of exactly identical genetic code with the remainder of the human population, the 1% difference per person is the main point of interest for DNA investigation and matches to suspects and other samples. Of this 1% of the remaining genetic code that is distinguishable from other humans, only a maximum of 13 alleles are analysed from each sample, of these 13 alleles that can be analysed and compared, many are lost, damaged or rearranged when collecting samples and isolating the DNA, leaving room for misinterpretations of the samples, with identical matches of all 13 alleles only being found once in every billion instances.
As well as the scientific issues with only being able to analyse 13 alleles to make certain placements, the lack of regulation within laboratories in its earlier adoption also led to frequent opportunities for samples to be misplaced, misused or completely swapped. This was particularly the case in Houston, Texas, where the forensics department has since been moved to another facility and is now overseen by non-government organisations as a result of numerous incidents of wrongful convictions with DNA evidence and misuse of samples.
As well as the post-collection aspects of the issues of DNA profiling, there is also the aspect of how DNA ends up at a crime scene. With many possible means of entry that vary by each case, DNA can simply be acquired from walking down the street, touching a door handle, using a knife to cook dinner weeks prior to the crime and numerous other means of acquiring DNA. As for these instances where DNA can be obtained from regular occurrences, DNA can also be completely transferred to completely different people via blood transfusions and blood bank donations, where donors can be mistakenly placed in crime scenes where they could not possibly have been. This is a large area for concern where microscopic fragments of DNA found on objects are copied and replicated to create a sample size large enough for the DNA to be analysed like a regular sample, not only implying the sufficient amount of DNA to place a person should a match to be found but also creating room for errors in the manipulation and copying of these microscopic fragments.
Overall, these marginal seeming instances can be what leads to wrongful convictions for extremely serious crimes, which when proven and victims of these are exonerated it can lead to scrutiny of police departments, forensic laboratories, individual scientists and even lawyers, where for each circumstance all of the person in question’s cases can be completely reviewed in high profile court cases.
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