The Use of Familial DNA Searching as an Investigative Tool

Eric J. Duvall – DNA Analyst Denver Police Department Crime Laboratory

Denver, Colorado

Familial Searching Basics

•  Investigators use the DNA database to search for near matches to solve crimes committed by relatives of the people in the database.

•  Siblings, parents, and children can be linked to crimes because their relative’s DNA closely resembles DNA found at a crime scene.

•  46% of inmates report that they have a close relative who has been incarcerated

Familial Searching Benefits

•  Familial searching saves both time and money in forensic investigations

•  Familial searching promotes justice by solving crime using technology and investigative means

•  Familial searching can provide leads in otherwise “cold” investigations

Familial Searching origins

•  In Great Britain, Familial DNA intelligence packages have been produced for 210 specific serious crime investigations.

•  Confined to ‘cold case reviews’ and ‘hard to solve’ serious crime investigations.

•  19% hit rate (40 of 210); variety of cases

Basic Concepts

•  Colorado SDIS as of July 2013 –  242,000 offender profiles –  9,000 forensic case profiles

•  85% of hits come from within state

•  Denver PD Strategy: Search all of Denver’s forensic

case profiles (single source 13 loci, source ID no) against Colorado offender profiles for potential familial links and rank results for follow-up

Project startup •  Initially we used DNA-View with Dr. Charles Brenner and searched about

1580 forensic profiles against 87,000 offender profiles – 137,600,000 comparisons

•  Method of search was optimized for parent-sibling and sibling to sibling matches.

•  Did not consider avuncular relationships •  Since then we have evolved our approach to familial searching and wrote

new software first in Excel now in SQL Server.

•  System runs on parallel processor setup on standalone workstation or server. Each forensic sample takes about 3 seconds to be searched against all offenders.

•  Ranked and generated report for all pairs that ranked with a LR of ≥ 200,000.

– Produced 32 pairs (13 included a female, 19 male) – Ran Y STR on all 19 male pairs

•  6 Y STR Matches on males-> follow-up •  13 Y STR exclusions

– Following up on all 13 female pairs

Results

Familial search investigations

•  Utilize NCIC and other web based databases

•  Create a family tree of possible suspects

based on the hit •  Contact family members as a last resort

Denver DNA Database Familial Searches-LDIS level

•  Parent LR 361,167 •  Sib LR 4,205 •  The father was in the

DNA database for a 2002 aggravated assault.

•  Y-STR DNA types matched.

•  Earwax on cell phone ear bud mixture 2002 Agg. Assault

Father of potential offender

Father   Mother  

First  Son   Second  Son   Third  Son  

First  Daughter  Second  Daughter  

First  Son  was  in  custody  at  the  6me  of  the  burglary.  

Second  Son    was  in  custody  at  the  6me  of  the  burglary.  

Denver DNA Database Familial Searches First Conviction in the US-SDIS level

•  6 loci shared/18 alleles •  Sib LR 558,845 •  Parent LR 1,669

•  Y-STR DNA types matched.

•  A conventional investigation led to the car thief’s brother and a warrant was obtained for the brother’s DNA.

Familial  hit  to  brother    Agg.  Motor  Vehicle  The4  Qualifying  offense  to  CODIS  

Denver DNA Database Familial Searches First Conviction in the US

•  Suspect charged with two car break-ins and pled guilty.

•  This is the first conviction in the United States

•  Conviction date: 9/10/2009

Brother  ID  by  database  search  41.1  executed  for  saliva  to  confirm  

Denver DNA Database Familial Searches First Conviction in the US

First case filed through familial searching •  2006 MVT case

matches •  Strong statistical

support that perpetrator of 2008 TFMV case is his biological brother (who fled to Mexico)

•  99.5% of U.S. population excluded from Y-STR profile

•  Case filed as John Doe and guilty plea entered Sept 2009

Y-STR Locus

2008 TFMV

2006 Stolen Motor Vehicle Case

DYS456 16 16 DYS389I 14 14 DYS390 24 24

DYS389II 30 30 DYS458 18 18

DYS19 13 13 DYS385a/b 13 - 14 13 - 14

DYS393 13 13 DYS391 9 9 DYS439 11 11 DYS635 21 21 DYS392 11 11

YGATAH4 12 12 DYS437 14 14 DYS438 10 10 DYS448 20 20

Colorado Familial Search Policy

•  Determined on case by case basis-letter to Director of CBI by Colorado Chief/DA. Significant public safety concern.

•  Standard investigative leads have been exhausted. •  6 month search routine is planned and allowed in policy. •  Arrestee search allowed in policy. •  Exigency recognized and searches can be done. •  Demographic information only released to LEA if investigators have

completed mandatory training course. •  Male to male requires Y-STR screening prior to information release.

Colorado Familial Search Policy

•  Policy requires confirmation sample to suspect via rule 41.1-Court Order for Non testimonial Identification.

•  Provides cautions to investigators about type of information and impact on

families. •  Colorado policy published 10/22/2009 and is available: •  http://www.denverda.org under DA Resources-> DNA-> Familial DNA

Database Searches •  Governor Ritter was briefed and suggested that State Legislators have

review. Safety Committee reviewed policy prior to implementation and had QA period. Strongly supported approach. State AG played key role in drafting and revising policy with CBI and DPD for most of 2008/2009.

Legal Issues for Familial Search of DNA Database Profiles

•  Crime scene DNA is abandoned

•  When individuals voluntarily abandon property, they forfeit any expectation in privacy that they might have had.

United States v. Jones, 707 F.2d 1169, 1171 (10th Cir. 1983)

Legal Issues for Familial Search of DNA

Database Profiles

•  The offender who left DNA at the crime scene has no standing to challenge the familial DNA search. They will not be charged with the crime.

•  Constitutional rights are personal and may only

be asserted by one whose rights are infringed. Rakas v. Illinois, 439 US 128, 133-134; 99 S Ct 421; 58 L Ed 2d 387 (1978).

States with Familial Searching

•  California

•  Colorado •  Virginia

•  Wyoming

•  Outreach of software to 27 states

U.S. Success

•  Grim Sleeper-California – At least 10 homicides from

1985-2007 – Familial search software

identified a link between the suspect and a son in July 2010

Resources

•  http://www.denverda.org/DNA/Familial_DNA_Database_Searches.htm

Contact Information

•  Eric J. Duvall Denver Police Department Crime Laboratory – DNA Section 1371 Cherokee St. Room 305 Denver, CO 80204 720.337.2043 eric.duvall@denvergov.org