The fatal stabbing of an elderly man on his mobility scooter by a psychotic ex-prisoner left a whole community “shocked” and “horrified”, police have said.

On Friday, Lee Byer was handed an indefinite hospital order at the Old Bailey after admitting the manslaughter of 87-year-old Thomas O’Halloran by diminished responsibility.

The court heard Byer was psychotic when he stabbed popular accordion player Mr O’Halloran in the neck and chest in August 2022.

Byer had served a 12-year sentence for robbery and was released from Wormwood Scrubs on bail five days before the attack in Greenford, west London.

Detective Inspector Laura Nelson told the PA news agency that the death of Mr O’Halloran had a “huge impact”.

“His loss is felt greatly within his family. He certainly showed no signs of slowing down in his old age. He was head of the family. He looked after his family, cared for them.

“He enjoyed playing his accordion and he was very well known throughout the community for that.

“I think the community were just shocked. Really, really horrified.”

She said she hopes the conclusion of the case will bring “justice” for the family.

The prosecution had “carefully considered” the case before accepting Byer’s plea to manslaughter in light of the medical reports.

Ms Nelson said the sentence of a hospital order would help protect the public.

“Ultimately, we’ve got to think about public safety and rehabilitation. Lee Byer will get the treatment that he needs in order to enable him hopefully to be well, so that protects in the future,” she said.

On the defendant’s criminal history, Ms Nelson said: “We know that he’d been released from prison five days prior to the attack.

“He’d been sentenced and had been recalled on licence for a robbery offence.”

The earlier recall to prison had been over a “harassment matter” and breaching a non-molestation order, she added.

On August 16 2022, Mr O’Halloran had travelled on his mobility scooter with his accordion on a shopping trip to Tesco.

As he made his way home, Byer left his address and the pair crossed paths in an underpass on the A40.

Ms Nelson, who led the Scotland Yard investigation, said: “Lee Byer attacked Thomas O’Halloran for absolutely no reason. There was no motive for it.”

She said emergency services were alerted within two minutes of the “brutal attack”.

The officer said: “It was a very fast-paced investigation. I had a team of people specifically working on trying to track the suspect’s movements from CCTV.

“We were fortunate that the area had very good coverage. We saw Byer exit the underpass still carrying a knife at this point. He had also got some gloves on.”

Police followed his progress through the subway and under the A40.

Soon after that, Ms Nelson said the face mask Byer was wearing fell down and he was seen to dispose of an item in a drain which turned out to be a handle.

The clear image of the suspect was circulated in the media with an “immediate” response from the public naming Byer, she said.

Meanwhile, the handle Byer had dumped in a drain was examined and found to have the DNA from both the victim and Byer on it.

Of the defendant, Ms Nelson said: “He was an unusual character. He denied the offence. Upon his arrest, he continued to deny being involved in the offence.

“Even when presented with the wealth of evidence that we were able to put to him, he still disputed his involvement.

“What we now know through a number of medical assessments is that he was psychotic.”