Under the federal system, if he cooperates with the government he'll get what they call a 4K letter, which allows a judge to ignore the sentencing guidelines and give him no jail. To get this, though, you typically have to provide evidence against someone else about crimes. He may want to start a new life, but he doesn't have to do it in the U.S. There are plenty of countries where he could live like a king without fear of extradition.