1. Combining DNA Evidence for Greater Match Information
American Academy of Forensic Sciences
February, 2012
Atlanta, GA
Mark W Perlin, PhD, MD, PhD
Cybergenetics, Pittsburgh, PA
Cybergenetics ©
Cybergenetics ©

2. Two DNA Mixture Samples
CSF locus in PowerPlex 16 kit
Sample 1
Sample 2

3. DNA Mixture Separation
Determine mixture weights of each sample
Sample 1
10% contributor
Sample 2
50% contributor

4. Joint Likelihood Function
MW Perlin, MM Legler, CE Spencer, JL Smith, WP Allan, JL Belrose, BW Duceman. Validating TrueAllele® DNA mixture interpretation. Journal of Forensic Sciences, 2011.
Joint Likelihood Function
Jointly explain data of multiple experiments
Sample 1
90%:10%
Another
contributor
genotype
12, 12
One contributor
genotype
10, 11
Sample 2
50%:50%

5. Probabilistic Genotype
Thoroughly examine all genotype explanations of the data,
assessing the likelihood of each one
Samples 1 & 2
Sample 1
Sample 2
objective

6. DNA Match Information 1 10 100 9.9 Sample 1 - 10 9.0 Sample 2 - 10
9.9
Sample 1 - 10
9.0
Sample 2 - 10
Samples 1 & 2
18.9 10

7. Massereene Barracks Attack
March 7, 2009 in Antrim, Northern Ireland
Homicide victims
Patrick Azimkar
Mark
Quinsey
Real Irish Republican Army claimed responsibility

8. Abandoned Burned Car

9. Touch DNA Evidence match stick at side of road passenger side
safety belt buckle
cell phone in
center console

10. Data Ambiguity D3 vWA D18 D2 DNA mixture D8 D21 D18 allele drop out
TH01
FGA
low DNA
quantity
no DNA
visible

11. Much Data, Little Consensus No Match Statistic
Brian
Shivers
Much Data, Little Consensus No Match Statistic 2 1 a b c

12. Joint Likelihood Functiona
TH01 locus
3 amplifications b c

13. Combining DNA Evidence
data
singles
pairs
all three
1.40
2.75 a a a b 25
560
1.43
4.60
6.04 b b a c a b c 27
40,000
1.1 million
0.75
4.42 c c b c 6
26,000
STR tests 10 20 30

14. Computer's Match Statistics
5.91 trillion
Colin
Duffy
6.01 billion
Brian
Shivers
1.1 million

15. The Honorable Mr. Justice Hart
Admissibility Ruling
December 1, 2011
The Honorable Mr. Justice Hart
18 page ruling on TrueAllele, concluding:
I am satisfied that the stage has now been reached in the case of this system where it can be regarded as being reliable and accepted, and I am satisfied that Dr Perlin has given his evidence in a credible and reliable fashion. In the light of these conclusions I can see no basis on which I could properly exercise my discretion … to exclude this evidence, and I therefore admit it in evidence.

17. E Pluribus Unum Out of many experiments, one informative solution