Dr. Perlins most recent Forensic Magazine article, DNA Matters: What Forensics Owes to Alan Turing.
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US11385955

Method, apparatus and computer software program for determining probability of error in identifying evidence

An apparatus for determining probability of error in identifying evidence includes a computer. The apparatus includes a non-transitory memory in communication with the computer in which is stored a software program, and prior and posterior probability distributions from a plurality of independent tests conducted on an item of evidence. For each test, the computer forms a factor distribution from the test’s probability distributions using the software program stored in the non-transitory memory of the computer. The computer convolves the independent factor distributions to form a joint factor distribution using the software program. The computer calculates a tail probability from the joint factor distribution using the software program to determine a probability of error in identifying the evidence. The computer stores the probability of error in the non-transitory memory. A method. A computer program.

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Claims: The invention claimed is:
  1. A method for performing a criminal investigation comprising the steps of:
    • obtaining a biological sample of a DNA mixture having DNA of at least 2 individuals;
    • comparing an evidence genotype from the DNA mixture with a known exemplar genotype to form a comparison;
    • expressing a probative value of a lead based on the evidence genotype as a likelihood ratio;
    • determining an error of the likelihood ratio;
    • and predicting how useful the lead may be in the investigation based on the error.
  2. A method for considering evidence of a crime comprising the steps of:
    • obtaining a biological sample of a DNA mixture having DNA of at least 2 individuals from a fire arm;
    • comparing an evidence genotype from the DNA mixture with a known exemplar genotype to form a comparison;
    • determining genotype probabilities and associated likelihood ratio values with respect to evidence from the fire arm and the comparison;
    • calculating error rates for the likelihood ratio values;
    • and assessing evidence based on its error rates for the likelihood ratio values.
  3. A method for recognizing an individual comprising the steps of:
    • determining a likelihood ratio from facial recognition of an individual;
    • calculating an error probability of the likelihood ratio;
    • and finding a risk of incorrectly identifying the individual based on the error probability.
  4. The method of claim 1 wherein the comparing step includes the step of determining a match statistic from the comparison.
  5. The method of claim 4 wherein the predicting step includes the step of identifying the evidence genotype is associated with a contributor to the DNA sample.