1. Virginia TrueAllele® Validation Study: Casework Comparison
American Academy of Forensic Sciences
February, 2013
Washington, DC
Mark W Perlin, PhD, MD, PhD
Kiersten Dormer, MS and Jennifer Hornyak, MS
Cybergenetics, Pittsburgh, PA
Lisa Schiermeier-Wood, MS and Susan Greenspoon, PhD
Department of Forensic Science, Richmond, VA
Cybergenetics ©
Cybergenetics ©

2. Case Composition • 72 criminal cases • 92 evidence items
• 111 genotype comparisons
Criminal offense
• 18 homicide
• 12 robbery
• 6 sexual assault
• 20 weapon

3. DNA Mixture Distribution

4. DNA Mixture Data Quantitative peak heights at a locus peak size peak

5. Data Summary – “Alleles”
Over threshold, peaks are labeled as allele events
Allele Pair
7, 7
7, 10
7, 12
7, 14
10, 10
10%10, 12
10, 14
12, 12
12, 14
14, 14
All-or-none allele peaks,
each given equal status
Threshold

6. CPI Information
2.26
CPI
6.70
Nothing reported 25

7. SWGDAM 2010 Guidelines Higher threshold for human review Allele Pair
7, 7
7, 10
7, 12
7, 14
10, 10
0%10, 12
10, 14
12, 12
12, 14
14, 14
Under threshold, alleles less used
Threshold

8. Modified CPI Information
2.26 56
CPI
mCPI
1.75
2.12
6.70
Nothing reported 25

9. TrueAllele® Casework ViewStation User Client Database Server
Interpret/Match
Expansion
Visual User Interface
VUIer™ Software
Parallel Processing Computers

10. Validated Genotyping Method
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):
Perlin MW, Belrose JL, Duceman BW. New York State TrueAllele® Casework validation study. Journal of Forensic Sciences. 2013;58(6):in press.

11. Separate mixture data into two contributor components
Mixture Weight
Separate mixture data into two contributor components
25%
75%

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

13. TrueAllele® Sensitivity
2.26 56
CPI
mCPI
TrueAllele
1.75
5.52
2.12
6.70
10.93
Nothing reported 25 9

14. TrueAllele® Specificity
True exclusions, without false inclusions
– 19.69

15. TrueAllele® Reproducibility
Concordance in two independent computer runs
standard deviation
(within-group)
0.305
log(LR2)
log(LR1)

16. TrueAllele® Virginia Outcomes
144 cases analyzed
72 case reports
9 trials
City
Court
Charge
Sentence
Richmond
Federal
Weapon
50 years
Alexandria
Bank robbery
90 years
Quantico
Military
Rape
3 years
Chesapeake
State
Robbery
26 years
Arlington
Molestation
22 years
Homicide
35 years
Fairfax
Abduction
33 years
Norfolk
8 years
Charlottesville
15 years

17. TrueAllele computer genotyping is more effective than human review
Conclusions
TrueAllele® Casework DNA mixture interpretation is:
A reliable method
• sensitive
• specific
• reproducible
TrueAllele computer genotyping is more effective than human review

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