The protective housing unit in Corcoran State Prison, about 50 miles south of Fresno, is considered the safest place for an inmate to reside within the California prison system. Designed to protect famous convicts from possible attacks, it houses mass murderers like Charles Manson, and high-profile criminals like Sirhan Sirhan, one of the first inmates placed in the unit, where he passed the time playing chess and working for 13 cents an hour as an administrative clerk.