The grandson of anti-gun campaigner Pat Regan has admitted killing her in a frenzied knife attack in Leeds.
Rakeim Regan, 20, stabbed Mrs Regan to death at a property in Marlborough Grange in the Hyde Park in May 2008.
Regan was ordered to be detained indefinitely at a secure psychiatric hospital at Leeds Crown Court.
The night before the killing, Mrs Regan had asked for him to be allowed home with her after he was assessed by a mental health nurse.
The court heard Regan was taken to accident and emergency at St James Hospital, in Leeds, following bizarre behaviour.
Mental Health Act
He was assessed by a mental health nurse who weighed up whether to release him with medication or to detain him under the Mental Health Act.
But Mrs Regan, who campaigned against weapons after her son was shot dead in Liverpool, asked for her grandson to come home with her.
Graham Hyland QC, defending, told the court: "It was Pat Regan's wish for him to come home with medication.
"Tragically that wish, borne out of her love and concern for the welfare of her grandson, cost Pat Regan her life the following morning."
Judge Peter Collier QC heard that Mrs Regan suffered a series of stab wounds to her head and neck when her grandson attacked her in her home in Leeds.
She was found with part of a broken knife embedded in her eye.
The court heard that Regan's mental health had deteriorated in the early part of the year.
In the days before the incident he had been arrested by police and after his release claimed officers had tried to rape him.
He also claimed aliens were trying to get him, and that "reptilians" were all over the place.
Jeremy Richardson QC, prosecuting, told the court that, as the defendant became more delusional, he claimed his grandmother was a paedophile.
After sentencing, Judge Collier asked whether health professionals could learn lessons for the future from the way in which Regan was dealt with at the accident and emergency unit.
He stressed he was not seeking to criticise anyone's decisions and said "hindsight is a wonderful thing".
Speaking after the case, Regan's solicitor, Grahame Stowe, said: "This is a very tragic case for Rakeim's family.
"It shows the clear dangers that follow when a serious mental disorder goes untreated."
Mr Stowe said his client had the "full support" of his family.
"They fully support Rakeim," he said. "Essentially, it was not his fault."
Regan will be detained at Rampton hospital, near Retford, in Nottinghamshire.