A schizophrenic man who killed a pensioner by axing him over the head was yesterday committed indefinitely to a psychiatric hospital.

Joseph Sheehan, 37, crept up behind Brian Messitt, 67, on a north London street and nearly decapitated him in front of terrified onlookers on March 14 this year. He later told bystanders: "I have known him for 20 years - it's complicated."

The court heard Sheehan, who pleaded guilty to manslaughter on the grounds of diminished responsibility, had long had paranoid delusions about Mr Messitt, including the belief that Mr Messitt was trying to kill him. For this reason Sheehan used regularly to visit the Old Bailey and watch murder trials, in order to gather evidence against Mr Messitt, whom he had first met as a 15-year-old.

On the day of the killing Sheehan was seen on Eton Avenue, Swiss Cottage, creeping up behind the victim. But for the horrific nature of the ensuing events, they looked like "actors in a pantomime", said prosecutor Richard Whittam. "Mr Messitt was largely unaware of the presence of the defendant and was struck on the head with an axe," he said. "He went to the floor and he was repeatedly struck."
A lorry driver who witnessed the attack said Sheehan axed Mr Messitt in the head five times. He described him as "having half his head missing" and said there was blood everywhere.

At first the psychiatrists who examined Sheehan thought he might have been watching murder trials at the Old Bailey so he could learn more about the "diminished responsibility" defence, in preparation for the murder he was planning.

But they later came to believe "there was no doubt he was mentally ill", Mr Whittam said.

The Recorder of London, Peter Beaumont QC, accepted the submission that Sheehan remained highly dangerous and was a "grave and immediate" risk to others, and committed him under the Mental Health Act 1983, with no time limit.

Sheehan is being held at Broadmoor high security prison but will be transferred to Chase Farm hospital, Enfield.