Issues and strategies in the DNA identification of World Trade Center victims

Identification of the nearly 3000 victims of the World Trade Center attack, represented by about 15,000 body parts, rests heavily on DNA. Reference DNA profiles are often from relatives rather than from the deceased themselves. With so large a set of victims, coincidental similarities between non-relatives abound. Therefore considerable care is necessary to succeed in correlating references with correct victims while avoiding spurious assignments. Typically multiple relatives are necessary to establish the identity of a victim. We describe a 3-stage paradigm--collapse, screen, test--to organize the work of sorting out the identities. Inter alia we present a simple and general formula for the likelihood ratio governing practically any potential relationship between two DNA profiles.