DNA statistics in the Simpson matter

On 3 October 1995, O.J. Simpson was acquitted of two murders in spite of very strong DNA evidence linking his blood to the crime. Although numerical statements describing the strength of this evidence were made, the DNA profiles included so many loci that the need for presenting numbers in this case, and in others using similarly high numbers of loci, is probably unnecessary. If numbers are to be presented, however, they should be given in the form of likelihood ratios. One thing the verdict in the Simpson case makes clear is that it is essential that the integrity of DNA evidence (with regard to collection, potential contamination or tampering) be beyond doubt.