Other crap? Probably DNA. If you suspect someone for various reasons, and then get a DNA match, it's almost certain that you have the right person. If, on the

Other crap? Probably DNA. If you suspect someone for various reasons, and then get a DNA match, it's almost certain that you have the right person. If, on the other hand, you have a DNA profile, and you search the 10,000,000 entry FBI CODIS database, there's somewhere between a 1 in 10k to 1 in 3m chance that you'll get a hit on someone other than the person who left the sample. This seems to be rather understudied. Prosecutors like to talk about the probability that two people chosen at random would match. But that's not the correct value when you use DNA to locate the suspect. One thing that would be useful would be for the FBI to report on collisions and near-collisions between known profiles added to the database.