The widow of a man stabbed to death by a schizophrenic has blamed failings in the mental health system.

Robert McKenzie, 43, had not been taking his medication when he killed 27-year-old father-of-two Chris Stones.

Today he is facing an indefinite sentence in a mental hospital after beating a murder charge but being convicted of manslaughter on the grounds of diminished responsibility.

After yesterday's hearing at Lewes Crown Court, Tabatha Stones, of Roedean Road, Worthing, said McKenzie should have been forced to take his medication and was "an accident waiting to happen."

The 34-year-old said: "It was a matter of time. Whenever McKenzie felt threatened he was going to use that knife.

"These people have too many rights. They don't need to comply with what the doctors are saying and they can just not take their medication if they want. It's a very dodgy area and I think it needs to be more clear-cut.

"Someone has got to take responsibility. If he is let out on the streets again, they have got to be sure there is no chance of him doing this sort of thing again."

McKenzie, known to friends as Mad Mike, has a history of paranoid schizophrenia and was cautioned by police and committed to a mental unit for ten weeks for carrying a knife in 2003.

The Shelley Road, Worthing, resident stabbed Mr Stones in the stomach after the pair argued in the street in nearby Pavilion Road in June last year.

During a week-long trial, the jury heard McKenzie had told psychiatrists he heard voices and believed doctors and police were against him.

He had been known to Worthing mental health services for some years, had alcohol problems and attended The Hollies, a drop-in centre for people with mental health problems.

But he refused to take his medication, believing it would make him worse.

Judge Richard Brown sectioned McKenzie indefinitely under the Mental Health Act.

Mr Stones' wife of five years said: "It is with great sadness that we have had to say goodbye in such a tragic and senseless way and such an awful loss to me as a wife, his children whom he loved dearly, his stepchildren whom he loved as his own, his mother, father, uncles and aunts, nieces and nephews and all of his friends - all of whom will always hold Chris in a special place in their hearts. Life will never be the same."

Mr Stones' father Chris, 53, from Hastings, said: "I have lost my son and my friend. We have lost everything."

Detective Chief Inspector Graham Pratt, of Sussex Police's major crime branch, said: "If McKenzie had not been carrying a knife, none of this would have happened.

"Whatever reason people have for carrying knives, there is always the risk that the situation they find themselves in escalates to a point which they had not contemplated."

A spokesman for Sussex Partnership NHS Trust said: "We extend our sympathies to the family. Robert McKenzie was known to us but there appeared nothing in his past history to suggest to those caring for him that he posed a danger to others.

"The trust is anxious lessons are learnt from this case and acted upon. We have launched an investigation into what happened and can complete that now the trial has finished."