Elderly man Leslie Trotman has died after a pitbull-type dog attack in Brentford, West London, Scotland Yard have said.
The 83-year-old was attacked by a dog that had escaped from a neighbour's garden. A man in his 30s was arrested on suspicion of manslaughter, following the attack.
Trotman suffered bite wounds to his right leg in the attack on 23 January, receiving further injuries when the dog knocked him over.
He was taken to hospital and released later that day, but his son found him dead at his home on January 29.
The incident was reported to police shortly after it happened, and officers spoke to Mr Trotman following his release from West Middlesex Hospital.
Scotland Yard decided to treat the matter as manslaughter after a post-mortem examination on February 2 revealed that Mr Trotman had died from a haemorrhage, caused by a ruptured spleen.
A police spokesman said: "Officers believe these injuries were sustained during the attack by the dog."
The matter has now been taken on by the force's homicide and serious crime command under Detective Chief Inspector Charles King.
Mr Trotman had been in his back garden in Rowan Road when he was attacked by the dog. It is not clear how the animal managed to escape and enter Mr Trotman's property.
Police arrested the suspect yesterday before releasing him on bail, pending further inquiries. Three dogs have now been seized from an address in Rowan Road.
Scotland Yard is asking anyone with information to contact them on 020 8721 4054 or call Crimestoppers anonymously on 0800 555 111.