BBC Focus - 04.2020_

DNA DETECTIVES FEATURE

HOW TO SOLVE

A CRIME WITH

GENETIC GENEALOGY

1.Crimeenforcementagency(policedepartment,
sheriff’soffice)contractsa DNAinvestigation
company to help them crack a cold case.

2. ThecompanyanalysescrimesceneDNAand
   convertsit intoa filerepresentingitsunique
   sequenceofbases (adenine, cytosine, guanine,
   andthymine).

3.Around700,000singlenucleotide
polymorphisms(SNPs)– themostcommonpoints
ofgeneticvariationbetweenpeople’sDNA– inthe
dataareexamined.AnExcelspreadsheetshowing
theinformationaboutthesepoints(loci)would be
26 columns wide and 851,000 rows long.

4. 
   

   SNPDNAanalysisis alsousedbyonline
   genealogyservicestofinddistantrelatives,while
   policeDNAdatabasesusea morebasicshort
   tandemrepeat(STR)analysis,whichallows
   identification of only close relatives.

   
   


5. 
   

   Thecompanyuploadsthedatafiletoa
   genealogyservicethathasagreedtobeusedfor
   lawenforcement,suchasGEDmatch.SNPsare
   comparedtohundredsofthousandsofother
   samples.Thegenealogyservicereturns a list of
   people who have DNA matches.

   
   


6. 
   

   Geneticgenealogistsemployedbythecompany
   usethisinformationtofindcommonancestors,
   buildfamilytreesanddeducelivingdescendants
   whomightfitthetime and place of the crime and
   other evidence.

   
   

Curtis,genomicresearchfellowat theUniversityof Queensland,

saidthatthegrowthof bothforensicgeneticgenealogyandDNA

phenotypinghighlightstheneedforgreaterprotectionof genetic

data.“Policegenealogyshowshowoneperson’sdecisionabout

theirgeneticdatacanimpactnotonlycloserelatives,butdistant

ones,”saysCurtis.“DNAphenotypinghighlightshowmuch

sensitiveinformationiscontainedinourgeneticdata.”This

includesinformationaboutourpredispositiontodisease and

mental health problems, as well as what we look like.

PRIVACYCONCERNS

Someoftheconcernhasdampeneddownasgenealogywebsites

havemadeitclearerwhetherornottheyareusedinlaw

enforcementprogrammes,andnowmakeit necessaryforusers

to‘optin’if theirDNAis tobeusedforensically.Parabonsaysit

onlyuploadssamplestoGEDmatchandnowanothercompany

calledFamilyTreeDNA.Otherancestrysearchcompanies,suchas

Ancestry.comand23andme,donotallowaccessforcrime-solving.

Moore,whowasa well-knownancestrydetectiveintheUS

beforeshedevelopedforensicgeneticgenealogytechniqueswith

Parabon,alsohadearlyconcernsaboutusing DNA designated

forfamilyhistoryworkforcrime-solving.

Nowherconcernis thatnewprivacyrequirementsareshrinking

theDNApoolthatcrimesamplescanbecomparedagainst.Last

year,GEDmatchopteditsentiredatabaseoutof lawenforcement

matching,andrequiredeachpersonusingtheserviceto actively

opt in. The result is that Parabon now has just 200,000 people 2

ABOVEIn2018,

informationobtained

fromgenetic

genealogysites

allowedpoliceto

finallytrackdownthe

suspectedGolden

StateKiller,former

policeofficerJoseph

JamesDeAngelo

(pictured).He’d

carriedouta seriesof

rapesandmurdersin

the1970sand1980s,

buthadmanagedto

avoid capture