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Quick take: 5 common myths about genetic genealogy investigations

People fear what they don’t understand. Here’s a look at misconceptions and the facts


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By Police1 Staff

While the use of genetic genealogy to eventually crack the Golden State Killer case was such a watershed moment for investigations that we named it one of our top law enforcement gamechangers of the 2010s, police use of the direct to consumer services FamilyTreeDNA and GEDmatchPro has not been without bumps in the road. The novel solution to approaching cold cases has been a magnet for controversy arguably since the Golden State Killer breakthrough first made headlines. Chief among those concerns are questions around privacy, even leading some states to push back on how police agencies can use genetic genealogy services. There’s a lot of information flying around regarding police use of this investigative technique, and some of the most often-parroted sentiments are misguided.

Stephen Kramer and Stephen Busch, who co-founded the FBI’s forensic genetic genealogy (FGG) team, recently hosted an ISHI webinar titled “An Inside Look at the Facts and Fiction Surrounding Genetic Genealogy,” in which they repeatedly stressed the importance of “protecting the technique.” In addition to being thoughtful and careful in how investigative techniques are used, one of the other critical steps to preventing things like FGG from coming under fire to an unmanageable degree is to dispel myths and misinformation. Among the topics Kramer and Busch covered were five common myths about using genetic genealogy in investigations. People tend to fear what they don’t understand, and it’s important to know where there are misunderstandings and how to address them. Here’s a look at these misconceptions and the facts.

Myth #1: LE can (and will) use this technique to investigate any type of crime.

A common misconception is that genetic genealogy is being leveraged for the full scope of crimes and investigative work. FGG is being used for high-priority cases like crimes involving serious violence such as homicides and rapes, as well as ongoing threats to public safety and national security (like serial killings, kidnappings and bombings).

Myth #2: LE is looking at the private genetic code of innocent third parties.

LE doesn’t look at actual private genetic code when using genetic genealogy websites. Investigators only look at a shared percentage of DNA between people – determining how much a suspect’s single nucleotide polymorphism (SNP profile) has in common with a third-party SNP. Busch compared it to having the suspect’s phone number and using a direct-to-consumer database to find out if any of the phone numbers in the database share commonalities with the suspect’s. Law enforcement never sees the third party’s entire phone number, they’re simply told what percentage of the numbers match. On these ancestry services, this is shared in the form of centimorgans, which tell investigators how distant or closely related someone is to someone else.

Myth #3: LE has special access to public databases.

A common sentiment is that law enforcement agencies are getting some kind of special access or backdoor keys to ancestry websites, or the information they’re getting is somehow different than what the average consumer can pay to access. But the fact is police investigators access these databases and see the same things on direct-to-consumer services as the public does, according to Busch.

Myth #4: The technique will lead to wrongful convictions.

As the drive to use this investigative technique in stacks of cold cases increases in agencies across the country, one of the biggest fears the public has is that the use of FGG will result in wrongful convictions.

Busch explained that when going through the technique the way law enforcement investigators use it, grabbing the “wrong” guy is impossible. As outlined by Busch, the process of using FGG broadly consists of:

  • Uploading DNA and finding people the suspect shares common DNA with
  • Using the proximity of the suspect’s “genetic distance” from these “relatives” to triangulate where the suspect might be
  • Evaluating the totality of the circumstance before honing in on a suspect
  • Confirming the suspect’s DNA matches the crime scene DNA before anyone is arrested

FGG is a tool used as an investigative lead, but not as the mechanism for an arrest. Probable cause must be established, including the aforementioned comparison of the suspect’s DNA to the DNA at the crime scene.

Myth #5: LE use of genetic genealogy is “more invasive” than traditional investigation.

The sense that FGG is somehow more “invasive” than other traditional investigative techniques likely stems from its newness. Busch pointed out numerous “standard” techniques, such as surveillance, search warrants and interrogations, to underscore how much less invasive FGG is – a process that essentially consists of:

  • Putting the crime scene DNA into a public database
  • Seeing shared percentages of DNA
  • Using open-source research to triangulate who the suspect could be
  • Collecting the suspect’s DNA and confirming the match

For additional insights from Kramer and Busch’s experience working with FGG, including work on the Golden State Killer case, access the full webinar here.