Questions were being raised this week as to what caused a normally gentle and caring father-of-two to turn into a killer.

Adrian Johnson stabbed one 49-year-old man to death and injured another in a knife attack at a shared home for vulnerable adults in the early hours of May 4.

Mr Johnson, 27, who had been diagnosed with schizophrenia, was discovered dead in his cell at Belmarsh Prison on Thursday, May 13.

The former warehouseman, had been charged with stabbing to death 49-year-old Robert Anthony Lewis and with assaulting Colin Buckfield at a house in Cheam Road, Sutton, on May 4.

Mr Lewis, who stayed at the address in Cheam Road, died after suffering stab wounds to the arm and leg in the attack in the early hours.

Friends of Mr Johnson are now asking whether these two deaths could have been avoided and whether Mr Johnson, received the proper care for his illness from the authorities.

Friends revealed Mr Johnson had been in and out of care his whole life but, until the events of May 4, was not a violent person.

He is understood to have run out of his medication over the bank holiday weekend prior to the attack.

A friend said: “There are questions every step of the way, from who was responsible for ensuring Adrian had his meds, to the care he received from the South West London and St George’s Mental Health NHS Trust, to the care he received at High Down and Belmarsh prisons.

“If we thought he could have done this we wouldn’t be saying anything, but we can’t accept what has happened. It is totally out of character.”

One source said: “He would end up in hospital or a social unit and then he would be sent home with a bunch of pills and they never saw him again.

"He was passed from organisation to organisation."

On the weekend prior to the murder of Mr Lewis, Mr Johnson had visited his mother’s home in Wallington because he was feeling unwell.

After he left his mother’s house, Mr Johnson returned to the supported housing in Cheam Road he had been placed in by the trust last June.

Day-to-day affairs at the house are run by Croydon Churches Housing Association, which advises tenants on debt management as part of an independent living scheme.

The association takes people from a mix of backgrounds, including single mothers, ex-prisoners and young people.

Mr Winslet, chief executive of the association, said: “This is an independent living scheme. It is not about counselling.”

At 4.22am on May 4, Mr Lewis was found at the Cheam Road address with stab wounds to his arms and legs.

Friends of Mr Johnson said they did not think he was fully aware of what he had done and when the ambulance arrived it was Mr Johnson who let in the paramedics.

They said: “Once he was back on his meds in prison he became lucid and realised what he had done.”

Mr Johnson was first moved to High Down Prison in Bansted, where he attempted to commit suicide, then he was moved to Belmarsh Prison.

Although initially under 24-hour suicide watch at Belmarsh, this was later reduced to a 15-minute watch and then, between noon and 12.30pm on Thursday, 13 May, to an hourly watch.

Two hours later he was found hanging in his cell.

A spokesman for South West London and St George’s Mental Health NHS Trust said: “The case will be subject to an independent review and any learnings found as a result appropriately followed.

“We are not at this time able to discuss Mr Johnson’s care in any detail, but the trust ensures care is available to service users at all times.

"A crisis line is available to service users 24-hours-a-day, 365-days-a-year.”

A representative of Mr Johnson’s family said: "Our hearts and sympathies go out to the family of Mr Lewis."