Regarding fingerprints, let's not forget that non-police system (eg. biometric passports) only register a subset of flat prints. On French passports, only two f

Regarding fingerprints, let's not forget that non-police system (eg. biometric passports) only register a subset of flat prints. On French passports, only two fingers are saved, and the prints are 'flat' - not rolled . Those are usable as a verification (is the holder of the document the actual owner?), but would prove very hard to use to identify someone out of a crowd (whose prints are on this gun/knife/glass?).