SAN JOSE (AP) — Three Northern California jail guards accused of beating to death a mentally ill inmate have also been charged with assaulting another prisoner, prosecutors announced Tuesday.The three Santa Clara County jail guards were arrested last week after Michael Tyree, 31, was found beaten to death his cell shortly after midnight Aug. 27.The three guards were formally charged with murder Tuesday. Prosecutors also charged the three with assaulting inmate Juan Villa the night Tyree died.Guards Jereh Lubrin, Rafael Rodriguez and Matthew Farris appeared in court Tuesday, but they didn’t enter a plea. They remain jailed in Alameda County without bail.Rodriguez denied involvement in Tyree’s death in a jailhouse interview with the San Jose Mercury News published Sunday.“These men violated the law, human dignity, and the job that they were sworn to do,” District Attorney Jeff Rosen saidAccording to court records, after a fresh clothing exchange the guards were searching for extra garments inmates may have hidden in their cells.