Police and authorities were warned that David Askew was being targeted years before he was found dead at his home in Hattersley, Greater Manchester, it emerged.
Tonight detectives were forced to insist they had done "everything" possible to protect him.
One neighbour said Mr Askew's ordeal had been "like bear- baiting".
Mr Askew, who lived with his brother, Brian, and wheelchair-bound mother, Rose, was found dead outside his house after police were told youngsters were causing an "annoyance" at his property last night.
Gangs - some of whom have anti-social behaviour orders for harassing the victim - had launched a "particular spate" of attacks recently, the officer leading the investigation said.
But Mr Askew's neighbour, Avona Davies, 49, said the torment had been going on far longer.
The shop worker said: "This has been going on for about 10 years. We have complained to the police and council and they put cameras in their back garden about three years ago.
"They tormented David for money and cigarettes. They harassed him every night without fail.
"For the past two or three weeks the harassment has moved to the front of the house, which never usually happened. Last night it started really early. I got home about 6.30 and it was already happening.
"We have stopped complaining for about 12 months because nothing gets done."
Police officers called to the address in Melandra Crescent last night discovered Mr Askew collapsed outside. He had not been attacked and was pronounced dead at the scene. Results of a post-mortem examination were expected later.
Chief Superintendent Zoe Hamilton, of Greater Manchester Police, said it was too early to say if criminal charges would follow as she defended the force's involvement with the Askews.
She said: "It's a sad fact that, if people are different in a community, sometimes they end up being targeted.
"I think we have done everything we can. The level of personal involvement my staff and housing officers have had cannot be stressed enough.
"I would like to make clear we don't believe David's death was the result of a physical attack and we would urge anyone who might have been involved in the incident before or any members of the community who know what happened and who was involved to come forward please."
Jonathan Reynolds, councillor for Longdendale, said officials confirmed that the local council had been aware of Mr Askew's plight for several years.
He discussed the issue with residents in 2007 and called for CCTV to be installed at his home.
Mr Reynolds said: "I do remember a meeting at the request of residents shortly after my election in 2007. We were told Dave was getting harassment. The main request from the council was to put up CCTV on his house."
There were tearful scenes among neighbours as news spread of his death.
Ms Davies said her neighbour was targeted because of his learning difficulties, adding: "They would torment him all the time. Sometimes it would be two of them, others it would be six kids or a big gang.
"David would throw money and cigarettes into our garden to get rid of them but they would always go back. That's why they did it.
"There had been screaming and shouting between the hoodies and David before but never physical violence.
"We have had our patio windows put through and David's windows were smashed lots of times because they would throw stuff. They hounded them."
She said his tormentors were aged 18 or 19, adding: "It's so sad it's come to this.
"That it has come to somebody dying for all these people to be around - the Press, the police and council - for something to happen."
A neighbour who lived near the Askews for 39 years said she saw his body on the ground under a white sheet outside the house.
She went on: "Not that many children live around here so this gang comes from elsewhere. They would come and bait David, he was a harmless soul.
"They would wind him up something dreadful. Every year the youngest brother would join in - the next generation."
The case has echoes of the death of Fiona Pilkington, 38, who was driven to such despair by abuse that she drove her car to a lay-by and set it alight while she and her 18-year-old disabled daughter sat inside. Their bodies were found in the family's Austin Maestro just off the A47 near Earl Shilton, Leicestershire, in October 2007.
An inquest into her death heard that Leicester Police logged 33 complaints from Ms Pilkington about a gang between 2000 and 2007, including 13 in the 10 months before her death.
