Colin Greenway, 56, was killed by his mentally-ill neighbour in Thamesmead, south London, on 15 June 2013.
He was found lying on the floor with knife wounds to the neck at the property in Abbotts Close at around 2pm.
Mr Greenway, who was registered disabled and used a wheelchair, was pronounced dead at the scene. A postmortem gave the cause of death as incised wounds to the throat.
On 16 June police charged his neighbour Daha Mohammed, 51 [2/02/62], of Abbotts Close, Thamesmead, with murder.
Mohammed pleaded guilty to manslaughter on the grounds of diminished responsibility on 7 October 2013.
The prosecution accepted his plea on the first day of his trial, 27 January 2014. Psychiatrists agreed he was suffering from a schizo-affective disorder at the time of the killing.
Mohammed was detained indefinitely under sections 37 and 41 of the Mental Health Act.
The Old Bailey heard Mohammed came to the UK seeking asylum in 1997 and had a long history of mental illness with several admissions to hospital.
From 2007 his condition was being managed in the community and Mohammed was known to be aggressive when he did not take his medication.
Other residents noticed his behaviour deteriorating in the days before the killing.
After the attack Mohammed handed himself in at Belmarsh Prison and confessed to killing his neighbour. He told police: 'When I went into his room I was not in my mind.'
Judge Stephen Kramer QC told Mohammed: 'You killed your neighbour who lived opposite you. You beat him about the head and body and cut his throat with a knife.
'Both psychiatrists are agreed that at the time of the killing you were mentally ill. You were suffering from a recognised medical condition in which symptoms of schizophrenia and a mood disorder co-exist.
'It is likely you were experiencing delusional ideas. In my judgement the defence of diminished responsibility is made out.
'I am also satsified that the nature and degree of your mental disorder makes it appropriate for you to be detained in hospital for medical treatment.
'It is clear to me that if you stop taking your medication you pose a serious risk to members of the public if still at large.'
Mr Greenway's sister Sue Livingstone said in a statement read to the court: 'The day of the call about his death was unbearable. I wondered who could have done such a thing to Colin. He hadn't got a bad bone in his body and was in a wheelchair.'