A patient detained under the Mental Health Act was able to leave a secure psychiatric unit after the front door was left unlocked and later went on to kill an elderly church warden at her home, a court heard.
David Parish, 38, randomly attacked Beryl Purdy with a large golf umbrella he had taken from her porch and inflicted fatal head injuries.
Before the attack, Parish had locked Mrs Purdy's husband, Peter, in the kitchen of their home in Broomfield, near Bridgwater, Somerset.
Parish was suffering from paranoid schizophrenia caused by smoking cannabis and had been detained temporarily under the Mental Health Act at the Rydon Ward in Taunton.
Bristol Crown Court heard he had been able to leave the unit on March 27 2023 after the front door had been left unlocked.
Anna Vigars KC, prosecuting, said after leaving the unit, Parish had travelled to the vicinity of Mrs Purdy's home.
Her body was discovered after her husband had alerted a neighbour because he had been trapped in the kitchen by Parish. It was another neighbour who found her body behind the freezer.
"He then noticed two feet with black shoes on sticking out from behind the displaced fridge freezer," Mrs Vigars said.
"He went to investigate and found that the feet belonged to the body of Mrs Purdy, which was crumpled against the wall with a washing basket on top of her.
"Mrs Purdy’s head was covered in blood to the extent that it was difficult to see what her actual injuries were."
A post-mortem examination found Mrs Purdy had died from blunt force trauma head injuries consistent with the use of the umbrella.
At a previous hearing, Parish, of Halyard Drive, Bridgwater, pleaded guilty to manslaughter by reason of diminished responsibility.
The father-of-two's mental health had deteriorated following the breakdown of his marriage in 2021.
The court heard that Parish believed he was receiving messages from birds and that he was under threat from people outside his home.
The day before the attack, he was assessed under the Mental Health Act and detained at the Rydon Ward in Taunton.
"It was there that his parents went to visit him on Monday March 27," Mrs Vigars said.
"Mr Parish seemed to them to be calmer. After a little time of family chat, Mr Parish said he wanted to use the toilet and he left his parents.
"He didn't return to his parents and they raised the alarm with staff at reception.
"Staff apologised, telling the family that the front door to the unit should have been locked, that the police had been alerted to the disappearance and that Mr Parish had been reported as a missing person."
The court heard an investigation is underway into the circumstances of how Parish was able to leave the unit.
The judge, Mr Justice Saini, asked: "What accountability has there been for the hospital that allowed Mr Parish to walk out? It is not Mr Parish's fault that he left.
"He was clearly meant to be detained under section two of the Mental Health Act. What's happened?"
Mrs Vigars replied: "As I understand it, there is an ongoing investigation. It may well be that the conclusion of this process will allow that process to make some progress."
In a victim impact statement, Mr Purdy said he and his family had been let down by the NHS.
"My lifetime partner and best friend, Bez Purdy, was brutally attacked and killed in our home," he said.
"I'm reminded of the incident every time I enter the room where she was found, which leaves me with anger and sadness, and more recently, loneliness to contend with every day."
"I miss my wife terribly and wish we could share the memories we had over the 64 years of marriage that we shared."
Mr Purdy said he was temporarily living in a care home while he recovered from injuries sustained in recent falls but planned to return home.
"I'm nervous to return home, knowing that one day Bez's attacker will be released back into the local community," he said.
"I feel let down by the NHS and the mistakes that were made that led to the death of Bez and the length of time it's taken to sentence the man that killed her."
The couple's son, Nick, said his mother's death has had a "lasting and damaging impact" on all members of the family.
"Hearing that someone had brutally attacked Bez in her home was distressing enough," he said.
"To then learn that she died from her injuries was unbearable. Nothing can prepare you for that news."
He added: "We will for ask the reassurance that what we've suffered could not possibly happen to anyone else."
Adam Vaitilingam KC, defending, said Parish's mental health had stabilised and he was no longer on medication.
"He feels intense shame about what he did and genuine remorse for what happened," he said.
"He should have been and could have been kept secure, and in our submission, that is an important mitigating factor as well."
Parish was jailed for six years and told he would serve at least two-thirds of the sentence in custody before he could apply for parole.
Passing sentence, Mr Justice Saini said: "You killed Beryl Purdy when you attacked her in her own home with a large golfing umbrella.
"You had been detained in the unit under section two of the Mental Health Act and you should not have been able to leave the hospital.
"The psychiatric experts agreed that at the time you killed Mrs Purdy, you were in an episode of schizophrenic psychosis that reduces what would be murder to manslaughter.
"Your psychosis was, however, precipitated by the use of cannabis.
"Mr Purdy's health has meant he cannot be here. He is reminded of the incident every time he goes into the room where she was found.
"Their son, Nick Purdy, has described how distressing it is to lose his mother because the door was left unlocked, and a man who should have been detained was able to enter his parents' home and kill his mother in such a violent way."
Speaking after the sentence, Detective Inspector Debbie Hatch said: "This was a deeply tragic incident in which Bez lost her life in the most distressing of circumstances inside her own home.
This case highlights the complex intersection between mental health and criminal justice."
A spokesman for the Somerset NHS Foundation Trust, which runs the mental health unit, said: "Our thoughts are with both families at what we realise will be a very difficult time.
As is standard practice with tragic incidents like this, we conducted a full root cause analysis investigation to understand and review the unit's environment, to identify if there are any areas of learning that we can take forward for our future care and support to patients and families.
This includes a review of security arrangements on Rydon ward, where appropriate changes have been made."