1. Finding Truth in DNA Mixture Evidence Innocence Network Conference April, 2013 Charlotte, NC Mark W Perlin, PhD, MD, PhD Cybergenetics, Pittsburgh, PA Cybergenetics © 2003-2013

2. DNA Mixture Data Quantitative peak heights at a locus peak size peak height

3. Peak Thresholds Threshold Under threshold, don't use alleles Allele Pair 7, 7 7, 10 7, 12 7, 14 10, 10 0%10, 12 10, 14 12, 12 12, 14 14, 14 Simplify data for human review

4. Allele Dropout Threshold Under threshold, use alleles anyway Allele Pair 7, 7 7, 10 7, 12 7, 14 10, 10 > 0% 10, 12 10, 14 12, 12 12, 14 14, 14 Conjure phantom peaks

5. Human Interpretation Issues Evidence call good data inconclusive peaks are too low for them too many contributors to handle potential examination bias Database hit by association, not by match comparison: make false hits restrict upload: lose true hits

6. TrueAllele ® Casework Evidence preserve data information use all peaks, high or low any number of contributors entirely objective, no bias Database hit based on LR match statistic sensitive: find true hits specific: only true hits

7. Validation Studies Perlin MW, Sinelnikov A. An information gap in DNA evidence interpretation. PLoS ONE. 2009;4(12):e8327. Perlin MW, Legler MM, Spencer CE, Smith JL, Allan WP, Belrose JL, Duceman BW. Validating TrueAllele ® DNA mixture interpretation. Journal of Forensic Sciences. 2011;56(6):1430-47. Perlin MW, Belrose JL, Duceman BW. New York State TrueAllele ® Casework validation study. Journal of Forensic Sciences. 2013;58(6):in press.

8. Separate Mixture Contributors 25%75%

9. Genotype Thorough: consider every possible genotype solution Objective: does not know the comparison genotype Explain the peak pattern Better explanation has a higher likelihood Victim's allele pair Another person's allele pair Allele Pair 7, 7 7, 10 7, 12 7, 14 10, 10 98%10, 12 10, 14 12, 12 12, 14 14, 14

10. Handgun @ locus TH01 Three person mixture Lab says: inconclusive

11. TrueAllele mixture interpretation Genotype probability distribution Thorough & objective

12. Handgun does NOT match suspect Computer statistic AGAINST match

13. Informative TrueAllele genotype Expected match statistic: million/billion Search a DNA database for the right man?

14. The Search for Truth M. W. Perlin, "When good DNA goes bad," Journal of Forensic Research, S11:003, 2013. M. W. Perlin, "DNA Identification Science," in Forensic Sciences, volume 3. C. H. Wecht, Ed., Albany, NY: LexisNexis Matthew Bender, Chapter 37C, 2012. M. W. Perlin. "Forensic science in the information age." Forensic Magazine, 9(2):17-21, 2012.

15. More information perlin@cybgen.com http://www.cybgen.com/information Courses Newsletters Newsroom Presentations Publications