Infamous wife-killer Scott Peterson got an ass-whoopin' from another inmate in a California state prison -- in an altercation over pickleball, TMZ has learned.
Multiple sources confirm to TMZ ... Peterson got into the heated confrontation Sunday in the yard near his housing unit at Mule Creek State Prison, about 40 miles southeast of Sacramento.
Our sources say Peterson hit the ball directly at the other inmate, triggering the assault.