Use of ‘Familial DNA’ & What it Could Mean in Regards to Sex Crimes

“Familial DNA” is a topic that has come to the attention of many who had never heard of the term until recently when the Golden State Killer, an alleged murderer and serial rapist, was arrested by California authorities who had used the DNA of former policeman Joseph James DeAngelo’s family members to track him down.

Currently there are several states that have protocols in place to use familial DNA in criminal cases. These include Arizona, California, Colorado, Florida, Michigan, Minnesota, New York, Ohio, Texas, Utah, Virginia, Wisconsin and Wyoming. iStock_000015311791_Full-2-300x200

How does familial DNA work in tracking criminal suspects?

In many cases a suspect’s DNA profile may never have been entered into a database due to the fact he or she hasn’t been arrested or convicted of a crime. In this case, kinship may be the next step. Simply put, a familial search involves running an alleged offender’s DNA through the database in order to determine if his or her DNA may be genetically similar to a family member’s DNA when that family member does have a profile in the database due to a prior arrest, prosecution or conviction. This may produce a “near match.”

Another instance in which familial DNA was used in order to convict a suspect was in the case of the Grim Sleeper , a man who was arrested in for reportedly committing murder and attempted murder in Los Angeles over a lengthy time span. Lonnie David Franklin Jr. was arrested in 2010, and in 2016 found guilty by a jury for the murder of one teenage girl and nine women. He as sentenced to death in August of 2016.

In this case, the DNA found at the crime scenes were linked, although there was no exact DNA match in the state’s profile database to Franklin. At this point, police searched for profiles that revealed sufficient similarity for police to assume a family or “familial” relationship at which point they discovered DNA that was similar to that found at the crime scenes but that belonged to Franklin’s son. Since his son’s DNA was similar to his own, Lonnie David Franklin Jr. AKA the Grim Sleeper must be the killer.

How do popular websites like come into play?

Police don’t always stick to DNA databases such as CODIS (Combined DNA Index System) when searching for DNA matches. Given the popularity of ancestry and DNA services like, and, some law enforcement officials have used similar sites in searching for DNA “hits” or matches. In the Golden State Killer case detectives used, however the company has informed members that are uncomfortable with this that they may remove DNA profiles. and 23AndMe do not make this information available to police.

Serial killer mysteries from decades ago are now being “solved” using familial DNA, but is this ethical – and what does it mean for those suspected of sex crimes or other criminal offenses?

Technology and forensic science have come along way since the 70’s and 80’s, when fingerprints, blood typing and hair analysis was about all investigators had at their disposal. DNA analysis was used for the first time in 1986 to solve a crime. Given computers, DNA and advanced technology, today police can often do in seconds or minutes what used to take weeks, months or even longer.

Still, is the use of familial DNA ethical? Without a doubt familial searching has proven successful in some of the most recognized cold cases such as the Golden State Killer, but is it ethical or even fool-proof? The truth is, this type of searching casts an extremely wide net which could possibly violate the Fourth Amendment (the right to be secure against unreasonable searches and seizures). Additionally, mistakes can be made and often are, even when using traditional DNA search. Familial DNA is a much wider search and often includes siblings, parents, children, spouses, even cousins or grandparents. This is especially true with DNA sites such as

While family members with similar DNA may not be in a criminal database, they may certainly be on some of the genealogical sites. Ultimately, it’s easy to see how someone who is innocent or even a family member could become a suspect in a sex offense or any crime they have absolutely no connection to.

Privacy issues abound, and people of color are particularly impacted because they are inordinately represented in DNA databases. Family members whose DNA is examined for possible connection to a suspect or even a crime often experience an enormous amount of stress and anxiety. Not only that, there is an enormous possibility that innocent people will be harassed by law enforcement and wrongly investigated; this can result in social stigma and even damage to an innocent person’s life.

Familial DNA is another tool for cracking sex crimes and other offenses, whether for good or bad. While it has proven effective for solving some of the most heinous cold cases, it could prove disastrous in others and leave innocent people facing criminal charges. Something to think about.

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