A man convicted of stalking Madonna and famously threatening to slash her throat from ear to ear has escaped from a Los Angeles psychiatric hospital, police said on Thursday.

Robert Dewey Hoskins (54), who was convicted in 1996 of stalking Madonna after telling her bodyguard that the star was meant to be his wife and scaling the wall of her Hollywood home, walked out of the hospital last Friday, a spokesman said.

"Hoskins is highly psychotic when not taking his medication and has very violent tendencies," said a Los Angeles Police Department statement, asking people in the Los Angeles area to be on the lookout for him.

Hoskins was jailed for 10 years in 1996 and after his release was transferred to a hospital, where he was determined to be a "mentally disturbed offender".

In July 2011, about a year after his release from that hospital, he was arrested again and sent to the Metropolitan State Hospital, southeast of Los Angeles.

In Hoskins' 1996 trial, Madonna testified that she had recurring nightmares after seeing the homeless drifter near her home in April 1995.

She said that her bodyguard reported that Hoskins said "he was there to take me away... that I was supposed to be his wife, that if he couldn't have me, he was going to slice my throat from ear to ear," she said.

Hoskins returned to her home the next month, while the star was in Florida, and was shot twice by a guard after scaling a wall and jumping into her swimming pool.

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