A mentally-ill son who killed both his elderly parents in a savage attack and then buried their bodies under a pile of furniture at their Norfolk home has been made subject to a hospital order - six years after the double tragedy.

Arthur Dunkley, 83 and his wife Marguerite, 80, were found dead at their home in Lyng, near Dereham, on June 12, 2005, after they had been attacked by their son Terrence Dunkley, 59, who had inflicted repetitive blows on the couple before stamping on them. A post-mortem examination found they had died from multiple injuries.

Former teacher Terrence Dunkley, who is a paranoid schizophrenic, was found unfit to plead at the time and has since been undergoing treatment at a secure unit in Norwich.

Psychiatrists have now assessed Dunkley as fit to plead and so the case was today brought back before Norwich Crown Court. Flanked by staff from the secure unit, Dunkley admitted the manslaughter of his parents, while suffering from diminished responsibility.

Ian James, prosecuting, said that Dunkley was a former geography and sport teacher and had moved to Norfolk with his wife, who was also a teacher.

However he said it was noticed that his behaviour began to deteriorate: 'He seemed to harbour strange ideas, for example he felt persecuted by a neighbour when he turned his light on and seemed to have delusions about messages on the internet.'

He said that Dunkley's wife eventually left him and and he used to visit his parents at their home in Lyng and there were disturbing incidents witnessed by neighbours. On one occasion Marguerite was seen coming out of the house screaming with her arms in the air and Arthur was being dragged out of the home.

Mr James said that on the day of the double killing the couple had been to church but at about 11am screams were heard from the property.

Mr James said that Dunkley's brother Nicholas had visited the home as he was concerned about his parents' safety but Dunkley had refused to let him in.

Police were called and the parents bodies were found concealed under a pile of furniture in the dining room.

He said that Dunkley appeared 'perfectly calm' and had smiled.

Mr James said that although police had been involved in relation to Dunkley's behaviour in the past his mother never wanted to press charges as he was her son.

Judge Peter Jacobs made Dunkley subject to a hospital order under which he will remain at a secure mental health unit, as he was assessed as still posing a significant risk of harm in the future.

Judge Peter Jacobs told Dunkley: 'These are very grave offences. Other family members had expressed real concern about your behaviour towards your mother and father. You were in a terrible violent temper calling them all sorts of obscenities. Both were killed by multiple injuries, you then concealed their bodies.'

He said the impact of the killings had a traumatic effect on the family as well as neighbours and the close-knit local community.

'This was clearly a case of diminished responsibility and the position has not changed.'

He added: 'The tragedy was you destroyed your own life as well as theirs.'

The court also heard from consultant psychiatrist Dr Ann Stanley who said that it was clear at the time of the killings that Dunkley was a paranoid schizophrenic and although since getting treatment he had made some progress he still was suffering from a mental disorder.