Mr Beith had been transferred that morning to a hostel for the mentally ill. At about midday, he set off to his local day centre for a cup of tea. He never arrived.
Mr Beith's life was irreversibly changed when he was injured in a fight at a local disco when he was 16. Shortly afterwards, he suffered his first nervous breakdown and was in hospital for six months. He started to shout constantly, but his parents were told his disturbed behaviour was due to family problems and was not due to a medical condition.
When he was released, his parents were unable to cope with him. 'Mark would leave the bath running, burn food and leave the door open,' his mother, Jean, said. 'And as my husband and I both work, the situation was just not appropriate. He got thrown out of a number of hostels and, when we asked for professional advice, we were told that it was Thatcher's Britain - there was nothing out there. We should put him on the street and hope that the police got hold of him.
'I asked a social worker where he should go and was told a bed and breakfast. It was then that the scales fell from my eyes. There are no proper provisions.'
One night, Mr Beith chased a girl home and broke a window of her house. He was arrested by police for brandishing a knife at her angry relatives and held on remand at Feltham youth custody centre. While in custody, his mental illness was recognised and he was transferred to Napsbury Hospital, in St Albans, now under threat of closure. It was not until 1990 that he was diagnosed at Charing Cross Hospital as being a schizophrenic.
In 1992, Mark was allowed to leave care and set up in his own flat. He received visits from a psychiatric nurse every three weeks, but without proper supervision he soon stopped taking his medication.
His mother believes that the situation was inappropriate. 'The social services said that, if they visited Mark more often, he would be under the impression that we thought he couldn't cope. But it was obvious he couldn't,' she said. 'After three months he had completely emptied his flat and thrown everything into the rubbish. He hauled his fridge and cooker down the stairs and painted pictures all over the walls.'
He was arrested near Edgware Hospital for trying to steal a car, but the police merely took him back to his wrecked flat. Soon afterwards, he admitted himself to hospital. It was during the subsequent transfer to yet another hostel that his suicide occurred.
'If Mark had been left in hospital, he would be alive today. If he had been put in an appropriate hostel, he would be alive. Dumping someone with a mental illness is wrong,' Mrs Beith said.
'The support is not out there. It is a failing of the system. Mental illness is not just a label . . . There is a great fear of mental illness and the public needs to be educated.'