Mackay attacked his victim in broad daylight

The High Court in Glasgow heard that 35-year-old Roy Mackay posed a serious risk to the public.

The court was told Mackay's mental illness was made worse by drink and drugs and that he required the level of security provided at the state hospital at Carstairs.

Psychiatrist Dr Douglas Gray, 50, told Lord Phillip that if Mackay went to prison where there was a possibility he could get drugs and dodge taking his medication, his mental state could worsen.

The court heard that Mackay told one psychiatrist that he thought he had been in a graveyard on the day of the attack and felt that death did not exist.

Blood clot

During an earlier hearing Lord Phillip heard how Mackay attacked his victim, George Williamson, in broad daylight as he returned to his home at Park Crecent, Liberton, Edinburgh, from his daily walk.

He pushed the old man against a wall, punched him on the head and threw him to the ground between parked cars before pulling a walking stick from his grasp.

Mr Williamson, sustained a blood clot on his brain and died in hospital a week later after lapsing in and out of consciousness, suffering seizures and developing pneumonia.

Mackay, 35, of Monksbarn Gardens, in Edinburgh, was originally charged with the murder of Mr Williamson in June last year, but the Crown accepted his plea of guilty to a reduced charge of culpable homicide.

Mackay is being detained at Carstairs

Mr Williamson was described as a frail man but fit for his age and still with his full mental faculties.

Mackay had served in the Territorial Army but was discharged in 1988 because of mental illness. He was diagnosed as a paranoid schizophrenic the same year.

Three days after the attack on Mr Williamson he handed himself into the Royal Edinburgh psychiatric hospital where staff found him to be "in an agitated state". He was rambling, but did not appear to be drunk.

Mackay's criminal record includes convictions for assault.

He has been in hospital, both voluntarily and detained under mental health legislation, and out in the community since being diagnosed as a schizophrenic.

Although psychiatrists considered that Mackay was sane and fit to plead, at least one considered he was of diminished responsibility because of his mental illness.