An 81-year-old patient has pleaded not guilty in the beating death of his 94-year-old roommate at a California rehabilitation center in an attack prosecutors said was triggered by the older man's singing.

William Leo McDougall pleaded not guilty to murder Thursday during his arraignment in Orange County Superior Court.

McDougall and Manh (mawn) Van Nguyen were both recovering from hip surgery at Palm Terrace Healthcare Center in Laguna Woods on Oct. 1.

Prosecutors told The Orange County Register that McDougall got mad because Nguyen was singing in Vietnamese, so he took a metal rod from the closet and hit Nguyen repeatedly in the head.

A nurse stopped the attack.

McDougall's bail is $1 million. If convicted, he could face 25 years to life in prison.


Information from: The Orange County Register, http://www.ocregister.com