Push him out the door! 600K to keep him? How many dangerous scumbags would that amount keep in prison?
If they release him he will still be paid for by the taxpayer. In the stead of the County Corrections paying his tab, Medicare or SSDI will pay.
Gas him, and everyone wins.
The prisons are built, his keepers are there anyway, and those costs go on whether or not he's imprisoned......just the way people don't seem to fathom that our military costs are pretty much the same, no matter where the troops are stationed.
Keep him right where he is.