1. Computer Interpretation of Uncertain DNA Evidence National Institute of Justice Computer v. Human June, 2011 Arlington, VA Mark W Perlin, PhD, MD, PhD Cybergenetics, Pittsburgh, PA Cybergenetics © 2003-2011

2. Uncertain DNA Evidence Evidence item Evidence data DNA LabObjectively Infer 10 11 12 Evidence genotype Suspect genotype 10, 12 @ 50% 11, 12 @ 30% 12, 12 @ 20% 10, 12 Compare Afterwards probability

3. Automated STR Mixture Analysis NIJ Award 2001-IJ-CX-K003 Provide quantitative DNA mixture analysis on a wide range of data. Handle known STR artifacts and adapt to new marker technologies. Interact well with users, including DNA analysts and reporting officers.

4. 90%70%50%30%10% 1, 1/2, 1/4, 1/8 ng Study Design: 40 Mixture Items 5 weights 4 dilutions 2 pairs Margaret Kline NIST

5. MW Perlin. Real-time DNA investigation. Proceedings of Promega's 16th International Symposium on Human Identification, 2005. Same Data, More Information computer human information

6. Computer = million x Human MW Perlin, MM Legler, CE Spencer, JL Smith, WP Allan, JL Belrose, BW Duceman. Validating TrueAllele ® DNA mixture interpretation. Journal of Forensic Sciences, 2011. computer human information 13.26 7.03 6.24 10 million 10 trillion

7. Information Results MW Perlin, A Sinelnikov. An information gap in DNA evidence interpretation. PLoS ONE, 2009. information DNA quantity

8. Computer v. Human MW Perlin, A Sinelnikov. An information gap in DNA evidence interpretation. PLoS ONE, 2009. information

9. Commonwealth v. Foley ScoreMethod 13 thousandthreshold 23 millionuse victim 189 billionquantitative probability modeling preserves information peak threshold discards information The DNA Investigator™ Newsletter, 2009 Same Data, More Information – Murder, Match and DNA homicide: 7% DNA mixture fingernail evidence

10. Predictably Preserves Information 15 loci 12 loci 67 information MW Perlin, A Sinelnikov. An information gap in DNA evidence interpretation. PLoS ONE, 2009.

11. Commonwealth v. Lyons homicide: DNA mixture evidence Victim's blood spatter pulsating spray from severed carotid artery 75% victim 25% other

12. Degraded DNA Mixture Degraded other DNA Victim DNA

13. Quantitative Mixture Evidence Quantitative peak heights at locus D8S1179 victim other Perlin MW, Szabady B. Linear mixture analysis: a mathematical approach to resolving mixed DNA samples. Journal of Forensic Sciences, 2001.

14. How the Computer Thinks Considers every possible genotype solution victim other Explains the peak pattern Better explanation gives a higher probability MW Perlin, MM Legler, CE Spencer, JL Smith, WP Allan, JL Belrose, BW Duceman. Validating TrueAllele DNA mixture interpretation. Journal of Forensic Sciences, 2011.

15. Objectively Infer Genotype victimother MW Perlin, MM Legler, CE Spencer, JL Smith, WP Allan, JL Belrose, BW Duceman. Validating TrueAllele DNA mixture interpretation. Journal of Forensic Sciences, 2011.

16. DNA Match Information Probability(evidence match) Probability(coincidental match) How much more does the suspect match the evidence than a random person? 6x MW Perlin. Explaining the likelihood ratio in DNA mixture interpretation. Proceedings of Promega's 21st International Symposium on Human Identification, 2010. LR = 6

17. Thresholds Discard Data Over threshold, peaks become allele events. Under threshold, alleles vanish. All-or-none allele peaks; ignore victim genotype Threshold

18. Thresholds Disperse Genotype Human mixture interpretation probability distribution other

19. Thresholds Discard Information Human interpretation is less informative 2x LR = 2

20. Likelihood Ratio Simple Statement A match between the suspect and the evidence is 9.5 trillion times more probable than coincidence. Computer Human 9,500,000,000,000 42,000 MW Perlin. Explaining the likelihood ratio in DNA mixture interpretation. Proceedings of Promega's 21st International Symposium on Human Identification, 2010.

21. Missed Allele Error > 100% The DNA Investigator™ Newsletter, 2011 DNA Intelligence and Forensic Failure – What you don't know can kill you

22. Human Information 25 case items inconclusive

23. Computer Information 25 + 27 more resolved

24. SWGDAM Triage Interpret DNA evidence Library of match information On-demand case report human stochastic threshold computer probabilistic genotype (3.2.2) resolvable inconclusive

25. Computer v. Human No competition information reproducible mixture resolution degraded DNA unsolved cases complex cases interpretation likelihood ratio crime impact 1,000,000x Validated 1, 2, 3, 4, … Quantified Solved Automated Easy & fast Explained Maximized People use computer tools to do a better job

26. Learning More www.cybgen.com/information Newsletters gentle introduction to ideas Courses for scientists and lawyers Presentations handouts, movies, transcripts Publications abstracts, manuscripts The science of quantitative DNA mixture interpretation