By PAUL THOMPSON

Last updated at 21:17 23 April 2008

A fifty stone bear described by his owner as "the best-trained grizzly in the business" has killed one of his handlers during a rehearsal for a film stunt.

Rocky, seen wrestling with Will Ferrell in the recent movie Semi-Pro, was with three trainers when he suddenly lunged at 39-year-old Stephan Miller.

The 7ft grizzly clamped its jaws around Miller's neck and sank its teeth into him.

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Randy Miller, Ferrell's stunt body double and the late Stephen's cousin, fights five-year-old Rocky on his ranch in California

The other two men tried in vain to pull Rocky away and eventually used pepper spray to subdue him but his victim died from loss of blood.

The fate of the five-year-old bear has yet to be decided.

But animal experts expect the grizzly to be destroyed as it will be deemed unstable around humans and having been hand-reared from birth it cannot be released into the wild.

The tragedy happened at the Predators in Action training centre based in the San Bernardino mountains, about 100 miles from Los Angeles.

The centre is run by the victim's cousin, Randy Miller. He was the stunt double for Ferrell in Semi-Pro, about a basketball star who wrestles a bear to promote his struggling team.

He and animal welfare officers will decide if Rocky should be put to sleep.

The California Department of Fish and Game launched an investigation but said it would not rule on the bear's fate because the incident happened on private property.

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Rocky in a scene with Ferrell in the comedy Semi-Pro

Grizzlies are found in the north-western U.S. and in Canada, and are a protected species owing to their dwindling population.

Rocky is one of two grizzly bears at the Predators in Action centre, which until now has had a perfect safety record.

Other animals on the 55-acre site include seven tigers, three African lions, a black bear and two cougars.

Randy Miller, who has refused to comment on the tragedy, won a World Stunt Academy Award for his work wrestling tigers in the 2000 Oscar-winning blockbuster-Gladiator.

He was Russell Crowe's stunt double in the scenes where he is attacked by a tiger while defending himself in a Roman arena.

Denise Richards, who runs a Californian wildlife sanctuary, said that trained animals which turn on their handlers are often destroyed.

"Even though it may appear that the bear attacked for no reason, there was a reason.

"You can train them and use as many safety precautions as you can, but you're still taking a chance. It's still a wild animal."