ISSN: 0022-1198
CODEN: JFSCA
Published Online: 1 May 1998
Page Count: 5

Using a Tree Diagram to Interpret a Mixed DNA Profile
Emes, A
The Forensic Science Service, Metropolitan Laboratory,

Evett, IW
The Forensic Science Service, Metropolitan Laboratory,

Lambert, JA
The Forensic Science Service, Priory House, Gooch St North,

Foreman, LA
The Forensic Science Service, Metropolitan Laboratory,

(Received 11 June 1997; accepted 17 September 1997)

Abstract

A recent case is described where the evidence of bloodstaining on a knife suggested that it was a mixture from the two victims. Interpretation of the evidence in this problem necessitated the formulation of several sets of multiple hypotheses which were analyzed by means of a tree diagram. The problem was then greatly simplified to one of comparing the two alternative hypotheses of most interest. It was found that results were robust to variation in the expert's judgment regarding the possibility that a mixture of blood was present on the knife.

Keywords:
forensic science, DNA typing statistical interpretation, mixed DNA profile, likelihood ratio, tree diagram, multiple hypotheses

Paper ID: JFS16171J
DOI: 10.1520/JFS16171J
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