Exploring Forensic Scenarios with True Allele Mixture Automation

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Exploring Forensic Scenarios ® with True. Allele Mixture Automation 59 th Annual Meeting American

Exploring Forensic Scenarios ® with True. Allele Mixture Automation 59 th Annual Meeting American Academy of Forensic Sciences February, 2007 Mark W Perlin, Ph. D, MD, Ph. D Pittsburgh, PA USA Employee, Shareholder, and Discussion of Commercial Products or Services Cybergenetics © 2003 -2007

DNA data So many cases, so little time generate review years meeting the data

DNA data So many cases, so little time generate review years meeting the data challenge

Do the best job possible • Look at all the good data • Ignore

Do the best job possible • Look at all the good data • Ignore the bad data • Consider every possibility • Obtain the most match information

DNA evidence person

DNA evidence person

DNA evidence person specimen

DNA evidence person specimen

DNA evidence person specimen STR data

DNA evidence person specimen STR data

DNA evidence person specimen STR data profile

DNA evidence person specimen STR data profile

DNA evidence person specimen STR data profile

DNA evidence person specimen STR data profile

Consider every possibility • every allele call • all mixing weights • stochastic effects

Consider every possibility • every allele call • all mixing weights • stochastic effects • stutter artifact • peak imbalance • specimen combinations

DNA profile ambiguity Use wild card [* b] data ab bb a b List

DNA profile ambiguity Use wild card [* b] data ab bb a b List possibilities [a b], [b b] Attach probability 0. 6 0. 4

Match DNA profiles Prob(specific) Match Information = Prob(random) Match Information logarithm – Very large

Match DNA profiles Prob(specific) Match Information = Prob(random) Match Information logarithm – Very large number: “billion” or 1018 Use the exponent: 18

Comparing interpretation via match information Information Wildcards 11. 9 Listing 15. 9 Probability 17.

Comparing interpretation via match information Information Wildcards 11. 9 Listing 15. 9 Probability 17. 2

Scientific calculator • interpret DNA • match DNA • database engine

Scientific calculator • interpret DNA • match DNA • database engine

Linear Mixture Analysis J Forensic Sci 2001 46 (6) 1372 -1378

Linear Mixture Analysis J Forensic Sci 2001 46 (6) 1372 -1378

"What if. . . ? " scenarios • process additional samples? • which samples

"What if. . . ? " scenarios • process additional samples? • which samples should be used? • is there too much data? • discard low quality data? • combine low signal data? • solve serial crimes? • how many mixture contributors?

Obtain DNA data

Obtain DNA data

Infer DNA profile

Infer DNA profile

Match DNA profile 17. 3

Match DNA profile 17. 3

How many contributors? "What if" scenarios

How many contributors? "What if" scenarios

Discard bad data

Discard bad data

Low-level informative data

Low-level informative data

Using informative data 7. 9

Using informative data 7. 9

Using informative data 7. 9 11. 4

Using informative data 7. 9 11. 4

Combine informative data 12. 9

Combine informative data 12. 9

Serial crime investigation 12. 9

Serial crime investigation 12. 9

Many sample combinations Which subset of DNA samples gives the most informative result? seven

Many sample combinations Which subset of DNA samples gives the most informative result? seven groupings

True. Allele scientific calculator • 20 interpret CPUs • 1 match computer • central

True. Allele scientific calculator • 20 interpret CPUs • 1 match computer • central database interpret match database

Combining low level data seven groupings

Combining low level data seven groupings

Do the best job possible • Look at all the good data • Ignore

Do the best job possible • Look at all the good data • Ignore the bad data • Consider every possibility • Obtain the most match information

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