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DNA Mixture Interpretations and Statistics - To Include or Exclude

J. Butler, A. Mitchell, M.W. Perlin, A.M. Schubert, J. Friedman and J. Spriggs, "DNA mixture interpretations and statistics - to include or exclude", Fourth Annual Prescription for Criminal Justice Forensics, American Bar Association Criminal Justice Section, New York, NY, 7-Jun-2013.


Materials from the ABA CLE program and Dr. Perlin's talk.

ABA program
PPTPowerPoint slides
PowerPoint handout
TrueAllele handout


DNA mixture interpretations vary among crime laboratories throughout the US even with the advent of the 2010 SWGDAM Interpretation Guidelines. Software packages are available to help crime laboratories determine if the defendant's or victim's DNA profile is included or excluded. And if the profile is included, there must be a statistic to demonstrate the significance of the inclusion. This panel will discuss the variance in mixture interpretations and statistics throughout crime laboratories in the United States.


Our focus is DNA truth and criminal justice. Yesterday was D-Day, so let us recall what Winston Churchill once said: "This truth is incontrovertible. Panic may resent it, ignorance may deride it, malice may distort it, but there it is."

Genotype models are more accurate than threshold methods. Computer models can preserve identification information in DNA evidence that helps make society safer. TrueAllele® computing is thorough and objective, and gives accurate answers that manual methods cannot.

Who cares about accurate DNA answers? Why does it matter?

  • The police want a highly effective DNA evidence database to help catch criminals. By uploading 100% of mixture evidence to the database, instead of the 10% used now, they have a better chance of solving crimes.
  • Most prosecutors are passionate about the truth. They want to try the right person, and convict the guilty, based on solid DNA evidence.
  • A defender wants to exonerate an innocent person. Exculpatory DNA evidence can provide that opportunity.
  • The courts care about truth. A scientific expert must tell the truth, the whole truth - and nothing but the truth. If the witness knows the true match information is 100 billion, but only reports a DNA statistic of 100, is that the whole truth?
  • The citizens who pay billions of dollars each year for forensics labs and DNA evidence want a return on their investment. They believe that everything that can be done to prevent rape and other crimes is really being done, not just what government finds convenient. The people expect to benefit from all that today's science has to offer, without excuses.

Cybergenetics shares these values of scientific truth and criminal justice. For the past 15 years, we have been bringing TrueAllele technology into the world to provide a robust solution for hard DNA problems.