Sarah Lawson was 12 when she first wrote in her diary that she wanted to kill herself.

Sarah Lawson was 12 when she first wrote in her diary that she wanted to kill herself.

By the age of 16, she was locking herself in her bedroom and cutting her arms and legs so badly that she needed hospital treatment and plastic surgery.

As she entered her twenties, her parents soon lost count of the number of times she attempted to kill herself or deliberately injured herself. The once-vibrant young woman tried to hang herself, took overdoses of sleeping pills, slit her wrists and once had to be rescued by a friend after she walked into the icy sea near her home in Worthing, West Sussex.

Yet for more than a decade, she was repeatedly let down by nurses, doctors, multi-disciplinary teams and the mental health system, all of whom failed to understand or treat her compulsive self-harming.

In the final week of her life, she had tried to kill herself three times, slashed at her arms until she was covered in blood and had been thrown out of a psychiatric unit when she was allegedly found in possession of cannabis.

Driven to the brink of despair and desperation, in the early hours of Easter Saturday 2000 her father James took matters into his own hands. He gave his daughter an overdose of sleeping pills, then smothered her.

He woke his wife, told her what he had done and called police. Mr Lawson was convicted of manslaughter on the grounds of diminished responsibility and given a suspended sentence.

Yesterday, an independent review criticised the mental health service in Sussex over the way Sarah was treated, saying she was failed by "fragmented" care, "poor and patchy" management of her problems and a lack of communication between the agencies involved. The review concluded: "In an atmosphere of a sometimes dysfunctional community mental health team and justifiable criticism, the needs of Sarah Lawson were often lost. She was frequently manipulated into the role of a patient in a mental health service which was at times woefully inadequate."

During one period, a psychiatric nurse suggested that Sarah merely needed a hobby.

Charities say that 250 people suicides a year are preventable but occur because of systemic failings in mental health provision. They warn that the lack of understanding among doctors of people who deliberately harm themselves means many hundreds of thousands are left in the same position as Sarah.

"Sarah lived in a world that was black," said her mother Karen. "She felt her illness was her fault. I asked her why she was doing it and she told me she just couldn't help it. Whoever we went to for help made matters worse. We were treated with hostility and contempt."

From 1997 until her death, there was just one period of six weeks in which the independent review said that Sarah's care was of a good standard.

Since her death, Mr and Mrs Lawson have divorced and both suffer from from depression.

Her father said: "I am not really angry at anyone, I just still mourn my daughter. I can't think in terms of ifs and buts and what should have happened. Looking back, I have no regrets."