Man, 83, kills his 94-year-old roommate over his bad singing

William Leo McDougall 
By: Shifra Unger 

(Scroll down for video) An elderly man with no criminal record suddenly went crazy and killed his elderly roommate.

An 83-year-old California man, pleaded guilty on Friday, to murdering his 94-year-old former roommate at a short-term care facility, two years ago.

Prosecutors alleged that William Leo McDougall fatally beat Manh Van Nguyen on October 1, 2010, because the victim was singing in Vietnamese and he was upset.

The two shared a room as they recovered from hip surgery at Palm Terrace Healthcare Center in Laguna Woods.

McDougall grabbed a metal bar from his closet and hit Nguyen in the head.

The defendant's lawyer disputed that Nguyen’s singing led to the assault.

"I think the evidence is not clear whether the other man was even singing or not," said the lawyer.

Loewenstein suggested that his client may have been affected by his health and medication given to him at the time.

"Mr. McDougall, having undergone a medical procedure, was certainly not in a normal state," Loewenstein said. "Further investigation revealed that a tragic scene developed, which was completely out of character for the man," he said.

Before the murder, McDougall lived a life free of crime, his lawyer said.

"There was nothing in his record, zero," said Loewenstein.

The lawyer negotiated a plea bargain for McDougall, but it was unclear what sentence will be recommended. Loewenstein declined to say what sentence his client will receive.

McDougall has apologized to the victim's family through correspondence transmitted by prosecutors, Loewenstein said.

"My client and his family have made it clear through the District Attorney's Office that he has a lot of remorse for everyone," said Loewenstein.

McDougall is scheduled to be sentenced on October 26, Loewenstein said.