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What is Familial DNA Matching, and Should Law Enforcement Agencies Utilize This Investigative Tactic

Familial DNA matching is used by law enforcement to find the relatives of suspects. To do this, law enforcement agencies utilize publicly available databases, such as Ancestry and 23&Me to conduct a search for potential family members related to DNA collected at a crime scene. This method is not always reliable and is sometimes seen as an infringement of privacy, or an unnecessary risk for innocent civilians. Also, the accuracy of the results depends heavily on the quality and quantity of the data in the public source. Many databases contain out-of-date or inaccurate information, which can lead to the wrong results. In addition, databases can contain a significant amount of false positives and false negatives, which often occur when two matching samples are too similar or too far apart. In addition, there are several privacy issues that come with the use of public source databases.


Why Would Law Enforcement Agencies Use These Databases?

A common question that arises in these cases is why law enforcement chose to utilize the publicly available databases to begin with. Local, state, and federal law enforcement agencies have access to a private database called CODIS; or the Combined DNA Index System. Any time a DNA sample is collected from a suspect, and in some instances when an individual commits a crime, the DNA sample is submitted to this database. Then, when DNA is collected a crime scene, it can be run through CODIS and compared to known samples. However, when law enforcement agencies run the query through CODIS, the format is referred to as a high stringency search. This just means that the only results that will be returned in the search are exact matches. Publicly available databases allow for more relaxed searches, returning results that are partial, or potentially partial, matches. After matches are identified, law enforcement agencies can then begin eliminating familial branches one by one. When a familial branch cannot be eliminated, the police will then attempt to eliminate individuals within that family. One main issue with this is the sheer number of potential results returned. Hundreds, potentially thousands, of innocent families could be named as potential matches; and on the other side of that coin many potential matches may be excluded because of the inaccuracy of partial matches. Innocent civilians can be incorrectly identified as relatives of suspects, resulting in potential harassment. And although law enforcement claims to take steps to mitigate this issue, it is possible that innocent individuals could be targeted.

Familial DNA matches may also be somewhat biased, as they do not account for geographical or ethnic differences. This could potentially lead to incorrect matches or a lack of information about potential relatives. Overall, the use of public source databases for familial DNA matches may not be as reliable as law enforcement would like people to believe. Although the results may be able to provide some level of identification, the accuracy of the results can be questionable and there can be serious privacy and bias issues involved. It is important for citizens to be aware of the potential risks of this method and to take the necessary steps to protect their rights and privacy.


Are There Other Drawbacks To Familial DNA Matches?

Because of the relaxed parameters of a public database search, the number of potential matches is exponentially higher. Law enforcement may have to eliminate thousands of people before ever getting close to a suspect. Having to individually eliminate each person that may be a potential match to a DNA sample is time consuming, and can be financially draining for a small police department. In most cases, the time and financial commitment required cannot be justified.

The average person may not be fully aware that the information they submit to companies like Ancestry could potentially be accessed and used by law enforcement if desired. Recently, people have spoken out about potential invasions of privacy and infringement of rights regarding familial DNA matches. Opposition has retorted that if people don't have anything to hide they shouldn't be wary of their information being publicly available; however, there have many instances of investigators and evidence technicians fabricating or creating evidence. To blindly trust law enforcement agencies to behave appropriately during every investigation is naïve, and possibly even dangerous.


What are your thoughts of the use of Familial DNA Matches? Are they ethical? Are they reliable? Should people be concerned law enforcement is using these databases?

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