Richard Osborn-Brooks, 78, was arrested after taking on a suspected burglar at his home in south London.
A "burglar" who died after struggling with a pensioner during a break-in was a career criminal who helped con frail pensioners out of more £500,000 ($964,000) with his family.
Henry Vincent died from a stab wound after a burglary at the south London home of Richard Osborn-Brooks, 78, and his wife Maureen on Tuesday night. A second man remains on the run.
Vincent, 37, was once on a "most wanted" list and was named by police today as details of his criminal past emerged.
In 2003, members of his family were jailed for a total of almost 29 years at Croydon Crown Court after they conned pensioners out of £448,180.
He was in a gang with his father and five of his uncles operating in Kent and south London.
In November, detectives hunted Vincent after a distraction burglary in which a man in his 70s was targeted in Farningham, Kent.
A crying woman came to the front door of the elderly victim and said she had been attacked. But when she left the house, the elderly man discovered his front door had been left open and a jewellery box containing valuables had been stolen.
Osborn-Brooks was released on police bail after being questioned on suspicion of murder for several hours following his arrest.
Police have ordered him to return in early May.
His arrest sparked anger from neighbours and an online fund-raising campaign.
It has emerged that the pensioner - who was confronted by two intruders, one of them armed with a screwdriver - may have been trying to protect his wife Maureen.
Neighbour Nick Myatt said: "He's a lovely old man and he cares for his wife, who I think has dementia or is disabled. He's a nice man, nice to talk to. I hope the law sees sense and lets him off. I don't think it's right."
The decision to release Osborn-Brooks on bail means authorities have at least a month to decide whether to charge him as police continue to search for the second burglary suspect.
Police today appealed for the public's help in tracking down the second man who broke into the elderly couple's home and fled the scene.