Forensic investigative genetic genealogy – a huge leap for crime fighting

Law enforcement, military and other forensic experts around the world increasingly look to next-generation sequencing (NGS) for its unprecedented genetic insights, such as allowing investigators to infer unique attributes like hair and eye color and biogeographical ancestry.

NGS can highlight tiny genetic markers – so called single nucleotide (SNP)  variations – in crime scene DNA. Now, investigators can take it a step further and compare these same SNP patterns in family ancestry databases using Forensic investigative genetic genealogy (FIGG).

FIGG applies the same technology that platforms like 23andme and Ancestry use to find genetic relatives. It works with databases like Family Tree DNA and GEDmatch to find genetic family relationships to unsolved crimes amongst a pool of consenting individuals.

Solving cases with DNA is nothing new, but advances in the field and the use of genealogical databases can now help solve cold cases that were put on hold due to limitations in technology at the time.

FIGG is a quantum leap in forensics that will boost the fight against crime and the identification of victims of war and mass disasters.

FIGG making headlines

The most famous criminal case solved by Forensic Investigative Genetic Genealogy (FIGG) is that of the Golden State Killer, who was responsible for more than 100 violent crimes, including home invasions, rapes and murders in the 1970s and 80s. He had evaded capture for decades because his traditional DNA “fingerprint” did not match any existing profile in the police database. But his luck ran out when investigators uploaded DNA taken from an old crime scene sample to open-source genealogical databases, which led them to the relatives of Joseph James DeAngelo, an ex-cop turned truck mechanic. DeAngelo was finally arrested in April 2018 at the age of 72 and is serving multiple life sentences.

While traditional DNA fingerprinting cannot identify kinships beyond parents, siblings and children, so-called first-degree relations, FIGG can generate genetic associations to the fourth and fifth degree – great-great-great grandparents, first cousins once removed, great grand nephews and nieces. This means every sample used in FIGG can currently be linked to thirty to forty times more people than a traditional DNA fingerprint, which relies on so-called short-tandem repeat (STR) markers that are less informative over multiple generations.

This not only gives FIGG unprecedented power to solve recent crimes and the ever-rising number of cold cases like that of the Golden State Killer. It also heralds a step-change in the identification of casualties caused by natural disasters, other mass-casualty events and wars. For example, SNP markers could help identify unidentified victims of Russia’s attack on Ukraine, buried alone or in mass graves. Their SNP markers would be compared to those in a database of DNA samples donated by Ukrainians who are in search of missing loved ones.

The inter-generational reach of SNP markers means any database has to represent only a small minority of any population to guarantee substantial coverage. Whereas the 20 million STR analyses currently stored by the FBI in its “CODIS” database are a potential match for one US citizen in ten, the same number of SNP samples would link to 99 percent of the population. But getting these three-in-a-hundred citizens to volunteer their DNA to help hunt criminals or find missing people requires public confidence in how DNA data is used.

Succeeding in this endeavor

This technology is still relatively uncharted territory though, and governments around the world must pass laws to establish clear rules for the use of FIGG in criminal investigations and the identification of human remains. Denmark has recently adopted this technology following a parliamentary decision to enhance their investigative and forensic capacities and is creating the necessary framework that allows the use of FIGG. Others need to follow.

To succeed in this endeavor, governments must ensure that DNA samples volunteered in the course of family-history research cannot automatically be used for other purposes. Members of the public must explicitly opt in if they want their data to be made available to either human identification experts or law enforcement. It will also be up to the FIGG industry to demonstrate that it continually adheres to these rules. Trust in the technology is a key factor in its success.

Potential concerns about law enforcement over-reach and privacy breaches can be countered with clear regulations. In the US, the FBI is already helping local law-enforcement familiarize itself with FIGG and public state lab-networks are developing standard protocols for laboratories – both meant to reduce the conception that the technology is only warranted for high-profile cases. Increasing familiarity with FIGG will encourage law enforcement to tackle ever more cold cases, opening the way for more successes like the capture of the Golden State Killer.

And these will breed even more successes if the media communicate them widely. Experience shows that voluntary opt-in rates go up every time a cold case is closed thanks to FIGG. Because every cold case solved has a huge effect on those involved, their families and their wider community: criminals are punished, in some cases, the wrongly accused are absolved, the families and friends of the victims finally find some form of closure – and those undecided about volunteering their DNA can be persuaded to opt-in. The more public acceptance FIGG can establish, the greater the quantum leap for forensics and public safety.