Tragic Sarah Lawson's mother, Karen, is separated from her husband but supports his helping their daughter to die.

After the court hearing she said: "Depression among young people is increasing. We need more and better facilities if tragedies like my family has endured become commonplace.

"I want to appeal to those who are in a position of power to investigate the level of care mentally-ill patients receive.

"Don't let there be another Sarah and another family traumatised by watching their child deteriorate before their eyes. Surely society cannot allow this to go on."

Mrs Lawson, who also suffered depression during her daughter's illness, described Sarah as "generous, funny, intelligent and good looking".

She said: "Family and friends loved her and still do. Unfortunately Sarah was mentally ill.

"She never hurt anyone and kept her suffering to herself, but for Sarah life was intolerable - deep dark depression interspersed with short periods of remission."

Mrs Lawson said her family was frustrated by not being able to get the right treatment for Sarah and felt her condition was not understood by the people who saw her.

"Getting the right treatment for Sarah proved impossible. At the very start my husband had to insist she be assessed by a psychiatrist, because her visits to the mental health hospital were once a week to see a nurse who suggested she take up a hobby.

"This was a serious suggestion made to a young woman who made regular suicide attempts and lacerated her arms so deeply they needed suturing and later cosmetic surgery.

"We could find no one in the area able to help and we were never even given a diagnosis or given advice on dealing with the situation.

"Each day was like living on a knife-edge, coming home and never knowing what we would find - would she be dead or covered in blood and burns.

"We went through this for approximately four years."

Mrs Lawson said they will keep asking questions about why she did not get the treatment she needed and calling for better care facilities for mental health patients.

"We need answers before we can put this dreadful time behind us."