If you get your DNA tested, your ge­netic data can be used to catch crim­i­nals

Law en­force­ment agen­cies have started in­ves­ti­gat­ing un­solved crimes by com­bin­ing DNA data­bases and fam­ily trees. But should ‘ge­netic ge­neal­ogy’ re­ally be used to crack cold cases?

Focus-Science and Technology - - CONTENTS - WORDS: JV CHAMARY

“If po­lice want a DNA sam­ple, they need your con­sent or a search war­rant – at least in prin­ci­ple”

From 1976 to 1986, the res­i­dents of Cal­i­for­nia were ter­rorised by a masked man who raped at least 48 women and mur­dered a dozen peo­ple. His care­fully planned at­tacks sug­gested mil­i­tary train­ing, but af­ter three decades, the East Area Rapist – also known as the Golden State Killer – seemed to have got away with his crimes. The case went cold.

Then on 25 April 2018, law en­force­ment of­fi­cials an­nounced that they had ar­rested Joseph DeAn­gelo, a 72-year-old Navy vet­eran and for­mer cop. In­ves­ti­ga­tors explained that se­men sam­ples from crime scenes had been used to pro­duce the per­pe­tra­tor’s DNA pro­file and search an on­line data­base for po­ten­tial rel­a­tives. The list of matches was then used to build a fam­ily tree that led to DeAn­gelo.

While catch­ing killers us­ing ‘ge­netic ge­neal­ogy’ might sound like an ob­vi­ous idea, it is by no means straight­for­ward. “Hu­mans are re­ally sim­i­lar ge­net­i­cally: if I com­pared my genome to yours, we’d be 99.99 per cent iden­ti­cal,” says Prof Gra­ham Coop, a pop­u­la­tion ge­neti­cist at the Uni­ver­sity of Cal­i­for­nia, Davis. “But there are po­si­tions in DNA which are vari­able be­tween in­di­vid­u­als.”


Mod­ern ge­netic tests read the let­ters of DNA at a se­lec­tion of po­si­tions across the hu­man genome to gen­er­ate a pro­file of ge­netic vari­ants. These sin­gle-let­ter dif­fer­ences rep­re­sent DNA re­gions that of­ten vary among peo­ple, called ‘sin­gle nu­cleo­tide poly­mor­phisms’ or SNPs (pro­nounced ‘snips’).

Per­sonal ge­nomics com­pa­nies like 23andMe and Ances­try of­fer ‘di­rect-to-con­sumer’ DNA tests that read about 700,000 SNPs. Those vari­ants gen­er­ate a pro­file that claim to re­veal your fam­ily his­tory, eth­nic back­ground and sus­cep­ti­bil­ity to dis­ease.

Ge­neal­o­gists who want to study a fam­ily tree in de­tail can up­load DNA pro­files to a site like GED­match, which com­pares SNPs shared by two peo­ple to cal­cu­late their ge­netic sim­i­lar­ity. The GED­match (GE­nealog­i­cal Data match) web­site stores pub­lic pro­files up­loaded by its one mil­lion users. Un­like pri­vate data­bases run by DNA-test­ing ser­vices like 23andMe, GED­match can be searched by any­one who reg­is­ters for ac­cess, which is how in­ves­ti­ga­tors found DeAn­gelo. “Find­ing these ge­netic matches is easy,” says Coop. “The ac­tual work the in­ves­ti­ga­tors did is the hard part.”

Catch­ing the al­leged Golden State Killer was a wa­ter­shed mo­ment in show­ing how com­bin­ing data­bases and fam­ily trees can help crack cold cases. “That re­ally opened up the po­ten­tial of what we would be able to ac­com­plish,” says ge­netic ge­neal­o­gist CeCe Moore, who pre­vi­ously fo­cused on cases of unknown parent­age, like adop­tion.

Moore now heads the new ge­netic ge­neal­ogy unit for Parabon NanoLabs, a firm that pro­vides foren­sic ser­vices to law en­force­ment agen­cies. Af­ter DeAn­gelo’s ar­rest, Parabon up­loaded more than 100 DNA pro­files to GED­match, with its per­mis­sion (in­ves­ti­ga­tors didn’t ask be­fore up­load­ing the Golden State Killer’s pro­file).

Moore’s first case was a dou­ble mur­der in Wash­ing­ton State. The male killer’s DNA pro­file was up­loaded on a Fri­day and by Satur­day she had a list of matches for build­ing a fam­ily tree that led to a mar­riage that pro­duced three daugh­ters and one son. By Mon­day, she had a name for the po­lice: Wil­liam Tal­bott II.

Parabon now of­fers a ge­netic ge­neal­ogy ser­vice to any agency, not just ex­ist­ing cus­tomers. With enough hu­man re­sources, it could help crack hun­dreds (maybe thou­sands) of cold cases. If DNA is available, the ap­proach could be ap­plied to other in­fa­mous crim­i­nals, such as the Zo­diac Killer, who mur­dered at least five peo­ple in the late 1970s and taunted po­lice with let­ters that might carry traces of saliva.


While it may seem that catch­ing bad guys can only be a good thing, there are le­gal is­sues to con­sider, es­pe­cially pri­vacy con­cerns for peo­ple whose DNA is stored in a data­base. What if your pro­file is down­loaded and leads to iden­tity theft? Or genes as­so­ci­ated with dis­ease or eth­nic­ity are used to dis­crim­i­nate against you when try­ing to get a job? Such sce­nar­ios could oc­cur in fu­ture.

For Amer­i­cans, the is­sue cen­tres on whether you’re en­ti­tled to a rea­son­able ‘ex­pec­ta­tion of pri­vacy’ un­der the United States Con­sti­tu­tion. “One of the big­gest pri­vacy pro­tec­tions is the Fourth Amend­ment, which pro­tects in­di­vid­u­als against un­rea­son­able searches and seizures,” says Dr Natalie Ram of the Uni­ver­sity of Bal­ti­more School of Law.

If po­lice want a DNA sam­ple, they need your con­sent or a search war­rant – at least in prin­ci­ple. In prac­tice, they can follow you un­til you dis­card DNA in a pub­lic place – such as saliva on a cof­fee cup – then law­fully grab a ‘sur­rep­ti­tious sam­ple’ (that’s how po­lice ob­tained DeAn­gelo’s DNA). It’s pos­si­ble be­cause you waive your rights to prop­erty when it’s been thrown away, the ‘doc­trine of aban­don­ment’. Even up­load­ing your pro­file to a data­base might be con­sid­ered ‘aban­don­ment’ un­der US law: in

the 1970s, the Supreme Court said the Fourth Amend­ment didn’t cover data vol­un­tar­ily shared with a third party.

What about here? For now, UK law only ap­plies to DNA pro­files for con­victed crim­i­nals. “Our Na­tional DNA Data­base is quite well-reg­u­lated in terms of who gets on it, who’s al­lowed to ac­cess it,” says Prof Ca­role Mc­Cart­ney of Northum­bria Uni­ver­sity. “But there’s no rules about pri­vate com­pa­nies – it will come down to their terms and conditions.” The Euro­pean Union’s re­cent Gen­eral Data Pro­tec­tion Reg­u­la­tion (GDPR) law gives cit­i­zens greater con­trol over how their in­for­ma­tion is han­dled, but Mc­Cart­ney thinks it’s ac­cepted that the po­lice can use ge­netic data. Bri­tish po­lice could search GED­match pro­files to track down suspects with Amer­i­can rel­a­tives.

Over-reach can hap­pen through ‘func­tion creep’ – when the use of new tech­nol­ogy (like DNA data­bases) is sneak­ily stretched be­yond its orig­i­nal pur­pose. This can cause an in­va­sion of pri­vacy, as il­lus­trated by the Na­tional DNA Data­base, which ini­tially added peo­ple who had been ar­rested but didn’t re­move them af­ter re­lease. The case ended up in the Euro­pean Court of Hu­man Rights and led to the Pro­tec­tion of Free­doms Act.

The dan­ger is com­pounded by mis­placed trust in the foren­sic process, which is vul­ner­a­ble to er­rors: in­ves­ti­ga­tors can cause con­tam­i­na­tion while col­lect­ing DNA, or mix up sam­ples while pro­cess­ing. De­spite what’s seen on TV po­lice dra­mas, DNA is rarely fea­tured in tri­als, which is when ex­perts ex­plain its re­li­a­bil­ity. “DNA evidence is seen to be so pow­er­ful, it’s very dif­fi­cult to de­fend your­self if you’ve got your DNA matched,” says Mc­Cart­ney.

If you’re a law-abid­ing cit­i­zen with noth­ing to hide, you may still be ask­ing your­self the ques­tion: where’s the harm in us­ing my DNA to help catch a killer? The an­swer de­pends on your per­sonal ethics and how you weigh the ben­e­fits for vic­tims against po­ten­tial costs to other peo­ple.

One key is­sue is in­formed con­sent. “I’m re­ally not con­fi­dent that peo­ple un­der­stand or are even aware that their ge­netic ge­neal­ogy can be used for crim­i­nal or foren­sic pur­poses,” says Dr Ben­jamin Berk­man, a bioethi­cist at the US Na­tional In­sti­tutes of Health. Un­til re­cently, he adds, in­for­ma­tion about such dis­clo­sures was ‘buried in the small print’.

Berk­man says the prob­lem stems from ex­pec­ta­tions. Peo­ple signed up to GED­match to study their fam­ily his­tory, not aid law en­force­ment. And al­though the site’s orig­i­nal terms of ser­vice did warn users that DNA pro­files could be used to help iden­tify re­lated to vic­tims or crim­i­nals, some mem­bers didn’t re­alise that un­til DeAn­gelo’s ar­rest hit the head­lines, then felt so mis­led that they deleted their ac­counts. GED­match has since re­vised its terms to ex­plic­itly state that pro­files could help iden­tify a per­pe­tra­tor of a vi­o­lent crime.

In­formed con­sent also means be­ing con­scious of the im­pact ‘fa­mil­ial search­ing’ could have on oth­ers. “I like to think about it in terms of your cousin get­ting ar­rested,” ex­plains Berk­man. “Some would say ‘The fact that my DNA in­di­rectly helped to lead him to jus­tice, it’s fine’, but you can imag­ine other peo­ple who would feel guilt or con­flict about hav­ing caused a rel­a­tive to go to jail.”


“In con­trast to the crim­i­nal jus­tice sys­tem, in the me­dia you’re of­ten guilty un­til proven in­no­cent”

When some­one is un­der sus­pi­cion for a crime, their name can get leaked to the press – and in con­trast to the crim­i­nal jus­tice sys­tem, in the me­dia you’re of­ten guilty un­til proven in­no­cent. That’s what hap­pened to US film-maker Michael Usry Jr, who was in­ves­ti­gated in 2014 for a 1996 mur­der, based on a par­tial match to his fa­ther’s DNA fol­low­ing a fa­mil­ial search of a data­base (the FBI even se­cured a war­rant for cheek swabs). Even if you’re later cleared, as Usry was, be­ing branded a killer could still haunt you for the rest of your life.

“At the end of the day it’s your genome,” Berk­man con­cludes. “And if you want to learn more about your ances­try or your ge­neal­ogy or your health, I don’t know that other peo­ple get to tell you what you can and can’t do with your DNA.”

But for ge­netic ge­neal­o­gist CeCe Moore, the eth­i­cal balance tips to­ward the vic­tims of crime and their fam­i­lies. “These fam­i­lies have of­ten been wait­ing for decades for jus­tice and some sort of clo­sure,” she says. “And we are fi­nally able to pro­vide that through this new tech­nol­ogy and tech­niques.”

TOP ROW: Joseph DeAn­gelo, the Golden State Killer, dur­ing his years as a po­lice of­fi­cer, and (right) a 1976 po­lice sketch of the killerABOVE: DeAn­gelo was fi­nally ar­rested in 2018. His case is on­go­ing

ABOVE: Michael Usry Sr with a pic­ture of his then 19-year-old son. Usry Jr was vil­i­fied on­line as a mur­derer due to par­tial DNA evidence, but was later found in­no­cent

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