BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Cell type determination and association with the DNA donor - Jacob de Zoete (Universiteit van Amsterdam) DTSTART:20161109T113000Z DTEND:20161109T120000Z UID:TALK68897@talks.cam.ac.uk CONTACT:INI IT DESCRIPTION:Co-authors: Wessel Oosterman (University of Amsterdam)\ , Bas Kokshoorn (Netherlands Forensic Institute)\, Marjan Sjerps (Kortewe g-de Vries Institute for Mathematics\, University of Amsterdam)

In forensic casework\, evidence regarding the type of cell material contained in a stain can be crucial in determining what happened. For ex ample\, a DNA match in a sexual offense can become substantially more inc riminating when there is evidence supporting that semen cells are present .

Besides the question which cell types are present in a sample\, also the question who donated what (association) is very relevant. This question is surprisingly difficult\, even for stains with a single donor. The evidential value of a DNA profile needs to be combined with knowledg e regarding the specificity and sensitivity of cell type tests. This\, to gether with prior probabilities for the different donor-cell type combina tions\, determines the most likely combination.

We present a Bay esian network that can assist in associating donors and cell types. A lit erature overview on the sensitivity and specificity of three cell type te sts (PSA test for seminal fluid\, RSID saliva and RSID semen) is helpful in assigning conditional probabilities. The Bayesian network is linked wit h a software package for interpreting mixed DNA profiles. This allows for a sensitivity analysis that shows to what extent the conclusion depends on the quantity of available research data. This can aid in making decisi ons regarding further research.

It is shown that the commo n assumption that an individual (e.g. the victim) is one of the donors in a mixed DNA profile can have unwanted consequences for the association b etween donors and cell types. LOCATION:Seminar Room 1\, Newton Institute END:VEVENT END:VCALENDAR