it depends on the seriousness of the crime. serious felonies have 20 years, except murder, which doesnt have one. less serious felonies are 6 years. Misdemeanors i think are 2 years , and minor misdemeanors are 180 or 90 days. these all apply to them finding out NOW about a crime you commited THEN. if they find out that you were involved in an armed robbery 40 years ago, they cant prosecute you on it today. if you murdered someone 40 years ago, they CAN prosecute you. warrants, on the other hand, never expire. if you robbed a bank today, and then fled to mexico, but they knew it was you and had a warrant for your arrest, if they catch you 25 years later, they can still bring you back and put you in jail. usually what they will do is convict you in absentia (meaning you are not there) and then whenever they catch you, you start your sentence.