This is America, we've put literal retards (as in people with IQs below 70) to death plenty of times, Chris is absolutely fit to go to prison. Like half the people in prisons in America have mental issues-- schizo, PTSD, depression, bipolar, borderline...
In some states the prison system is actually the largest mental health provider. There are people not mentally fit for society that basically get treatment in prison, serve out their sentence and get dumped onto the streets to be mentally ill and homeless again, where they then get caught with drugs or assaulting strangers or whatever and put back in prison. Chris can use a computer, drive, write a story, he's plenty functional by legal standards.
Due to the nature of his crimes he'd almost certainly end up in a special protective wing alongside other chomos (pedos), sex offenders, and troons. If he rages out a lot they'll give him some calming pills. But I see nothing about him that would make him qualify for an insanity plea or anything