As DNA evidence plays a profound role in conviction and release, its issues are elucidated.
There are several privacy concerns that have arisen with DNA collection. Most users of genealogy databases, where people provide samples of genetic information to private companies for insight into their genetic history, are unaware that law enforcement may be able to access their information and use it in court. The MIT Technology Review describes how “if a DNA database is large enough, practically everyone can now be tracked [through] their relatives,” even if they themselves had never submitted their DNA. To further underscore the vulnerability of a private database’s genetic information, they discuss a situation wherein national security is threatened: “If a foreign counterintelligence agency grabbed a million American DNA profiles, that country could use genetic genealogy to identify the true identity of American spies or diplomats, locate their relatives, or discover genetic kompromat like unacknowledged children.”
In order for DNA to provide sufficient evidence, it needs to be analyzed. New samples entered into CODIS are automatically screened against case samples from the crime scenes and individual samples from suspects and convicts. Unfortunately, the US has had an extreme backlog of DNA samples to enter and analyze for more than a decade. Each case has a statute of limitation – the deadline for filing a lawsuit from the time of the incident. Because of backlog and the prioritization of violent crimes over other crimes, such as property crimes and theft, DNA samples may be entered in much after the date of the incident. Thus, “even if these samples could help solve a crime, the crime can no longer be tried.” (Nature)
Nature also emphasizes how “retention of an innocent person’s DNA can be seen as an intrusion of personal privacy and a violation of civil liberties.” In 2022, a woman sued the city of San Francisco after DNA from her 2016 rape investigation was used to arrest her for a property crime. Under federal law, CODIS is not allowed to store victims’ DNA. However, there is “no corresponding law in California to prohibit local law enforcement databases from retaining victims’ profiles and searching them years later for entirely different purposes,” (CBS News) as the city had been storing samples from sexual assault victims in a private database. The California Department of Justice later informed law enforcement and the crime lab that storing victims’ DNA samples could violate the Fourth Amendment right to lawful searches and seizures; the charges against the woman were dropped, and the police department officially ceased to use DNA from victims of sexual assault and other crimes to investigate unrelated crimes.
Some issues with the use of DNA profiling stem, counterintuitively, from advancements in profiling itself. When previously, “a bloodstain for example, would have to be at least the size of a dime or quarter to elicit enough DNA for a profile,” today investigators can gather sufficient DNA from “minute numbers of skin cells left behind by a criminal.” This heightened sensitivity in DNA profiling has certainly provided many benefits but has also led to wrongful convictions on the basis of trace DNA, where someone who merely touched or casually handled an object of interest may become a suspect. Analyzing trace DNA by examining the few cells left behind by anyone who was present at the scene has yielded a high false positive rate.
In November 2005, retired taxi driver David Butler was arrested for the murder of Anne Marie Foy. The evidence: a partial match made to DNA found on her fingernails.
With trace DNA, there is not always a determination as to whether the person was in contact with the victim at the time of the crime, at some point before, or had simply come in contact with the same objects the victim had.
In Butler’s case, “The DNA samples from Foy’s nails were a complex mixture of profiles and only a partial match was found.” Furthermore, Butler had flaky skin, meaning he left a much larger sample of cells each time he touched something. This could have meant that his DNA “could have found its way on to Foy’s hands and hence her clothing…by Foy handling coins that had previously been touched by Butler.” (The Guardian) Butler was acquitted after 8 months.
In Italy 2009, Amanda Knox and her boyfriend Raffaele Sollecito were convicted with the murder of Meredith Kercher, with the DNA evidence seemingly pointing to them. Two main pieces of evidence: that Sollecito’s DNA was found on Kercher’s bra, and that Knox’s DNA was found on the handle of a kitchen knife belonging to Sollecito, while Kercher’s was found on the blade. When Boise State University Professor Greg Hampikian reviewed the process of the DNA collection, he noted that Kercher’s bra had been exchanged by many crime scene investigators, who may have accidentally left traces of Sollecito’s DNA on it. Additionally, Knox was an avid cook, while Kercher’s DNA on the blade was less than half of the admissible amount of DNA required by the FBI.
When Hampikian had his students do an experiment regarding the accidental transmission of DNA by the crime scene investigators, “they found DNA from a member of the dean’s staff on one of the knife blades. Yet that person had not touched or even been in the same room with the knives.” (Science.org)
It is therefore of utmost importance that DNA evidence is gathered and handled cautiously, as contamination may lead to an incorrect match putting innocent people behind bars.
Sources:
https://news.bloomberglaw.com/us-law-week/police-search-of-rape-victims-dna-tests-meaning-of-consent
https://www.cbsnews.com/news/rape-kit-dna-san-francisco-woman-arrest-lawsuit/
https://www.science.org/content/article/forensics-gone-wrong-when-dna-snares-innocent
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