James Lawson, from Hove, East Sussex, pleaded guilty at Maidstone Crown Court to manslaughter due to diminished responsibility.

The court heard that in April last year he helped his 22-year-old daughter Sarah kill herself after she had suffered more than 10 years of manic depression.

The court heard Sarah had a long history of self-abuse and trying to commit suicide.

Michael Lawson QC, prosecuting, told the court Sarah's mental problems had started to overtake her life when she left school aged 16 and developed an alcohol problem.

Rock star obsession

He said: "She used to tell her mother she could not go to work without drinking half a bottle of vodka.

"She was 16 and on Prozac at the time.

"Her problems started with her obsession with the band Manic Street Preachers and particularly [the] guitarist, Richey Edwards."

The court heard that Sarah first tried to commit suicide in 1999 by taking a lithium overdose.

After this unsuccessful attempt Mr Lawson first talked about helping his daughter, saying to his GP: "If Sarah was a cat or dog, someone would put her out of her misery."

The court heard that a week before she was killed, Sarah had made several attempts to harm and kill herself.

Hospital visits

She was becoming angry that nothing could be done despite visits to her GP and psychiatrists.

At the end of the week she was admitted to the psychiatric wing of Worthing Hospital in West Sussex, before a planned transfer to a residential home on Good Friday last year.

But on the same day a hospital worker saw her smoking cannabis and she was sent home.

The defendant contacted Worthing police station early on Easter Saturday to say he had killed his daughter.

He said he had talked with her for a couple of hours on Friday night, before the conversation turned to him helping her to commit suicide.

'Failed by the Health Service'

Mr Lawson told police he had taken part in the mercy killing as his family could take no more and he felt the NHS had repeatedly failed to help his daughter.

Philip Sapsford QC, defending, said: "What Mr Lawson was really saying to the police was this. 'I could not fail Sarah, like everyone else had. I had to do it and Sarah is now at rest'."

Justice Robert Nelson adjourned sentencing of Lawson, who has a wife, Karen, and a son, Jamie, 21, for reports from the probation service.

'Traumatic'

The defendant was released on conditional bail to return to the court at a date to be arranged.

Marjorie Wallace, chief executive of the mental health charity Sane, said: "This case brings into poignant focus just how traumatic an illness like manic depression can be.

"Only those who have experienced the mental pain of someone they are close to can understand the sense of desperation and hopelessness of families, who are all too often left without the help they need."

She said: "Sane receives thousands of calls from families in a similar desperate situation."

Ms Wallace called for more research into the causes of manic depression.