Police detection of crime depends in most cases upon a report by the victim, the public, or even the criminal himself. The crime may not be reported and thus go undetected because: the victim is vulnerable to prosecution (for example, for carrying a weapon or for suspicion of some other crime); the victim may accept such victimization as one of the risks of life; the victim or witnesses may not recognize an act as a crime (a brawl or a traffic violation, for example), or they may not correctly evaluate the gravity of the crime; a witness may not wish to "get involved" and thus will not place a report.