Assessing the implications for close relatives in the event of similar but non-matching DNA profiles

1. Assessing the implications for close relatives in the event of similar but non-matching DNA profiles Travis E. Doom, Mike L. Raymer and Dan E. Krane Wright State University, Dayton, OH Forensic Bioinformatics (www.bioforensics.com)

2. STR genotypes are very amenable to database searches • United States: 2.4 million entries (CODIS) • Great Britain: 2.1 million entries (National DNA Database) • Austalia: 18,000 entries (CrimTrac) • New Zealand: 16,000 entries • Others

3. STR genotype comparison outcomes Kind of match Investigation? Perfect match “Cold hit.” Non-matching Eliminate as suspect.

4. STR genotype comparison outcomes Kind of match Investigation Perfect match “Cold hit.” Non-matching Eliminate as suspect. Almost-matching Eliminate as suspect. Investigate relatives?

5. Possible positions of the accused: Kind of match Explanation Perfect match “I didn’t do it, my brother did it.” Non-matching “I didn’t do it.” Almost-matching “I didn’t do it. Neither did any of my relatives.”

6. A practical example of familial searching • In 2003, North Carolina’s SBI generates STR genotypes from evidence from a rape/murder in 1984. • STR results exonerate Darryl Hunt after 18 years in jail. • No perfect matches to the perpetrator’s STR profile are found with any of the 40,000 individuals in the NC convicted offender database. • One individual in the database, Anthony Dennard Brown, is found to match at 16 of 26 alleles.

7. A practical example of familial searching • Is there probable cause to investigate Anthony Dennard Brown’s brother?

8. A practical example of familial searching • Is there probable cause to investigate Anthony Dennard Brown’s brother? • “This is a real-time story. (It’s) something that we’re trying to get right, right now. Everybody wants to make use of the (DNA) databases’ incredible power. The question we’re all asking ourselves is: How do you strike the balance?” Angelo Della Manna, forensic biology chief of the Alabama state lab and an analyst in the Brown case. • “We believe in what we’re doing. If you want a debate, we say fine, bring it on.” Richard Pinchin, director of Britain’s Forensic Science Service familial searching program.

9. Current US rules on familial searching • The FBI is barred from performing familial searches. • New York and Massachusetts have specific statutes that authorize familial searching of their state databases. • California’s DNA database technicians report partial matches but only if they “appear useful.” • Virginia analysts only tell investigators about “very, very close” matches. • Florida analysts can only report matches of 21 of 26 alleles or better -- “men who have 21 alleles in common are almost always brothers.”

10. This slide intentionally left blank for Travis’ and Mike’s slides.

11. A practical example of familial searching • Is there probable cause to investigate Anthony Dennard Brown’s brother?

12. Likelihood ratios (LRs) for profiles with matching rare and common alleles

13. A practical example of familial searching • Is there probable cause to investigate Anthony Dennard Brown’s brother? • Detectives collect cigarette butts from Willard Brown. • Willard’s STR genotype matches at all 26 alleles. He has pled guilty and is serving a life sentence (plus ten years). • “We’re having a positive effect on cases (and) preventing additional victims. What’s wrong there?” Richard Pinchin, director of Britain’s Forensic Science Service familial searching program.

14. Should familial searches be done? • “We believe in what we’re doing. If you want a debate, we say fine, bring it on.” Richard Pinchin, director of Britain’s Forensic Science Service familial searching program. • “We can’t just open the floodgates and unleash this (without) rules to protect the freedoms and liberties of those who are potentially subject to intrusive searches. . . . (but) how could you not use (DNA)? It has tremendous potential as an investigative tool.” Frederick Bieber, Harvard University Medical School

15. Should familial searches be done? • “The average Joe on the street, if he knew what could be done (with DNA databases), he would be worried about privacy. I think the average Joe is right.” George Li, Virginia convicted offender database manager.