Oh, and this part was included in what I read:
People who have been convicted of crimes are more likely to have relatives that have been convicted of a crime, which would help the technique be successful. Bieber cited one study in which 30 percent of inmates surveyed said they had a brother who had also been in jail.
The study published today used a computer simulation to study how well the technique would work, if generally used. It used data randomly generated based on genetic principles, not information from real databases, meaning the results would have to be verified with real-world data.
A computer, the study said, could generate a list of near matches, ranked by how likely those people are to be related to the person whose DNA was collected at a crime scene. One possibility, the study's authors suggest, is to decide on an arbitrary cutoff, giving police access to only those partial matches that exceed a certain likelihood.
Something about that is just a bit creepy...