There is no charge for a past crime unless two conditions are met. The statute of limitations (a limit on the amount of time Law Enforcement can charge you for the commission of a crime; usually one (1) year) has NOT expired, and as always the burden of proof is on the State, meaning they have to prove it. Murder, however has no statute of limitations. Which means if you committed a crime when you were 20, and they can prove it 50 years later when you're 70, you can still be prosecuted.