A schizophrenic man who was in court for carrying a knife was there because health workers had turned their back on him, his sister claims.

Prem Dhall, 41, appeared at Oxford Crown Court yesterday after he threatened a PE teacher with a commando dagger while out begging.

But his sister Sushila said health services were to blame after failing to support him when the place he had called home for ten years was closed.

The county's mental healthcare trust has denied her claims.

Miss Dhall, 42, of Walton Crescent, Jericho, Oxford, said her brother's paranoid schizophrenia had been stable throughout the decade he lived at 18 Morrell Crescent, a supported house in Littlemore for people suffering severe and enduring mental illness. But Miss Dhall, a former Green city councillor, said his troubles began when Oxfordshire Mental Healthcare Trust signed over the service to Oxfordshire Group Homes, in March last year, and he was moved to an acute ward at Littlemore Hospital.

She said: "I place outright blame on Oxfordshire Mental Healthcare Trust. They raised his hopes by giving him a long period of stability for 10 years, then they took it away from him.

"They have completely ripped the rug out from under his feet. They have taken away all the skills he learned at Morrell Crescent and now he's homeless.

"It's hell all the time. All the time I'm afraid that someone will knock on the door to tell me he is dead."

Oxfordshire Healthcare Trust has issued a statement saying it gave an "appropriate level of support" to Dhall.

Yesterday the court heard that Dhall threatened Farshad Kayani with the knife in Portland Road, Summertown, on January 18 when he refused to give him money. Dhall, who initially denied having the knife, later told officers he had produced it in self-defence after Mr Kayani told him he had a knife.

Judge Niall Quinn, sentencing Dhall, made a section 37 order under the Mental Health Act, meaning he will be detained in a hospital to receive treatment.

Miss Dhall said her brother was a bright pupil at school during their childhood in Aberdeen, Scotland, but was diagnosed with vulnerable psychosis at 18, followed by paranoid schizophrenia in his mid 20s.

Because of his condition, he spent time in and out of prison and tried to commit suicide three times, until Miss Dhall invited him down to Oxford, where she had started a new life after her parents emigrated abroad.

Miss Dhall said her brother was eventually moved to Morrell Crescent, where he lived without problem for 10 years.

She said: "He thrives in an environment where there is a member of staff who can tell when he's getting ill. He doesn't do things like eat regular meals or keep to any type of routine. He's completely impulsive and can't budget.

"At Morrell Crescent, there was always someone around who could help him with meals and money, and things like that."

But last year, Dhall lost his place at the home when it was taken over by Oxfordshire Group Homes.

Miss Dhall said: "He was moved to an acute ward at Littlemore Hospital and just got very ill and angry. He was then moved to the Warneford Hospital, until he was transferred to an Oxford City Council-owned bedsit in Summertown last May.

"He instantly started getting into trouble with the council, who were not in a position to cope with his condition or help people like him, and was evicted.

"He got a big knife because he thought he was liable to be attacked. "After his arrest, he was put in prison on remand, and then moved to the Warneford under section. He was released two weeks ago, and told he had to find somewhere to live or he'd breach his bail conditions. He was in a bit of a state about it and then went missing.

"He is not one to complain and just accepts that life is horrible and that he'll be treated badly. Meanwhile the mental healthcare trust is arguing that they have nowhere for someone like him to stay."

Making the detention order Judge Niall Quinn said: "I am going to make a section 41 order, which places restrictions on your release from the hospital.

"This is made if I feel it is necessary for the protection of the public, and I have reached that conclusion in this case.

"You have a long and sad history of mental illness, aggravated by drug taking, and your offending behaviour, coupled with your lack of insight into your illness, leads me to this."

David Bradley, director of operations at Oxfordshire Mental Healthcare Trust, said: "When someone is discharged from hospital, we prepare with the patient a care plan for their care in the community. If, however, someone chooses not to accept our help or advice we are often limited as to the support we can provide.

"In this case, I'm satisfied that every effort was made to provide an appropriate level of support."