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Four person DNA mixture

Four person DNA mixture. State of Indiana v. Dugniqio Dishay Forest June, 2016 Evansville, IN. Clear plastic baggie containing a white rock-like substance 21 grams of crack cocaine Level 2 Dealing in Cocaine. Validation axes.

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Four person DNA mixture

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  1. Four person DNA mixture State of Indiana v. Dugniqio Dishay Forest June, 2016 Evansville, IN Clear plastic baggie containing a white rock-like substance 21 grams of crack cocaine Level 2 Dealing in Cocaine

  2. Validation axes Sensitivity. The extent to which interpretation identifies the correct person. Truly include, don't falsely exclude. Specificity. The extent to which interpretation does not misidentify the wrong person. Truly exclude, don't falsely include. Reproducibility. The extent to which interpretation gives the same answer to the same question. Concordant independent computer runs.

  3. Widespread acceptance Admitted after Frye or Daubert challenge in: California, Indiana, Louisiana, Massachusetts, New York, Ohio, Pennsylvania, South Carolina, Virginia, Australia & United Kingdom Crime labs use TrueAllele system in California, Louisiana, Maryland, South Carolina & Virginia Used in five hundred criminal cases in 35 of the 50 United States, for both prosecution and defense Reanalyzed World Trade Center DNA samples identifying 18,000 victim remains for 2,700 missing

  4. DNA mixture interpretation Lab Infer Evidence item Evidence data Evidence genotype 10, 11@ 20% 11, 11@ 30% 11, 12@ 50% 10 11 12 DNA from two people Compare Known genotype 11, 12

  5. Computers can use all the data Quantitative peak heights at locus D5S818 peak size peak height

  6. How the computer thinks Consider every possible genotype solution Third person's allele pair Explain the peak pattern Second person’s allele pair First person's allele pair Fourth person's allele pair Better explanation has a higher likelihood

  7. Evidence genotype Objective genotype determined solely from the DNA data. Never sees a comparison reference. 43% 22% 17% 6% 5% 2% 1% 1% 1%

  8. Prob(evidence match) Prob(coincidental match) DNA match information How much more does the suspect match the evidence than a random person? 2x 43% 17%

  9. Match information at 15 loci

  10. Is the suspect in the evidence? A match between the bag and Dugniqio Dishay Forest is: 24.9 trilliontimes more probable than a coincidental match to an unrelated African-American person 132 trillion times more probable than a coincidental match to an unrelated Caucasian person 161 trillion times more probable than a coincidental match to an unrelated Hispanic person

  11. Match statistics

  12. Match statistics Number of zeros in match statistic “logarithm” expresses information

  13. Forest convicted Found guilty at trial Level 4 Possession of Cocaine With aggravating factors Sentenced to 11 years in prison

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