Serial killer Mark Rowntree, who stabbed four people to death in a New Year killing spree, is now never likely to be released from custody after being convicted of threatening to kill his social worker.

The former public schoolboy, who butchered his victims in eight days in January 1976, has been sent back to Rampton top security mental hospital without time limit by a Crown Court judge.

Rowntree, 47, who has changed his name to Mark Evans, was sent to Broadmoor top security psychiatric hospital in the summer of 1976 after he pleaded guilty to manslaughter on the grounds of diminished responsibility.

His victims were Bingley widow Grace Adamson, 85; Keighley teenager Stephen Wilson, 16, who was stabbed at a bus stop in Eastburn; part-time model Barbara Booth, 24, and her three-year-old son Alan, who were stabbed at their home in Burley, Leeds.

Rowntree, formerly of Tranmere Park, Guiseley, also spent time at Rampton Special Hospital and Ashworth Hospital, Liverpool.

In 1991 he was moved to The Hutton Centre, a secure unit at St Luke's Hospital in Middlesbrough, where he has been detained since, and soon after there was speculation that he was on the verge of being released until publicity about him being allowed on day trips to an adventure park and pop concert caused an outcry.

Today, relatives of his victims were celebrating the fact that the mass killer, who was 19 when he committed the offences, will almost certainly not taste freedom again.

In January he appeared before a judge at Teesside Crown Court and pleaded guilty to three charges of making threats to kill social worker Kath Cogley last year at the hospital.

Sentencing him after the case was adjourned for two months to assess his medical needs, the Recorder of Middlesbrough, Judge Peter Fox QC, ordered that Rowntree be admitted to Rampton Hospital and detained without limit of time under the Mental Health Act.

Rowntree's solicitor, John Bradbury, said the judge's ruling had duplicated the order he had been previously subject to and would "clearly be a factor taken into consideration" in any question of him ever being released.

After the case, Stephen Wilson's sister, Maureen Hudson, said: "I am happy. It's terrific news.

"I had waited all these years for him to slip up and now he has shot his bolt. I am glad he is going to Rampton - he always hated it there."

Mrs Hudson, who now lives on the East coast, said her heart went out to the social worker but she was sure Rowntree would now be incarcerated for the rest of his days.

She added: "I will never, ever, try to forgive. Hopefully now Stephen and the others, and all the families, can truly rest in peace, knowing he will never get out."

A childhood friend of Stephen, who saw him dying on her doorstep after he had been stabbed by Rowntree, also welcomed the news of his lifetime detention.

The woman, who does not want to be named, but is in her 40s and still lives in Keighley, said: "It's great news that he is not going to be released and be a threat to anybody else. I am pleased because this is final."

But the woman said she believed prison was the right place for Rowntree to be held.

"He should be incarcerated for life in a high security prison. If he can threaten his social worker in hospital, then nobody is safe. There are still a lot of people out there in fear and they shouldn't have to live like that."

Keighley MP Ann Cryer said: "You cannot allow people like that to be out. Keeping him locked up for life is the best solution. I don't think you should ever consider letting such a man out.

"It would be nice to think that therapy could be given so he would become a decent law-abiding citizen, but there is clearly something very wrong with him and I doubt if any form of treatment, therapy or medication would stop him. If he has threatened his social worker he clearly hasn't changed."

Last year Rowntree told the T&A, in a series of exclusive interviews, how he had threatened to kill his social worker because she had told a mental health tribunal he had no remorse. And he spoke of his fears that he would be moved to a top security psychiatric hospital like Rampton.

He said: "I can't seem to have forgiveness for the social worker. I made a threat to kill her and I said that I still would - and I'm sad to say I still will. And if I can't I would pay someone to do it because I have inherited a lot of money."