A Johannesburg drug user has admitted setting fire to a crowded housing block to cover up a murder, triggering a blaze that killed 77 people, it was learned on Wednesday.
The 29-year-old South African was detained on Tuesday after coming forward to confess to an enquiry established to investigate the tragedy in August last year, police said.
Separately, a human rights observer who was present at the inquiry told reporters that the man had explained that he started a fire to cover up a murder during a bungled gangland beating.
In August, 77 people including 12 children were killed and scores injured as the blaze ripped through a five-storey building taken over for illegal housing in central Johannesburg.
It was one of the deadliest urban fires around the world in recent years and the disaster sparked a renewed debate about housing in South Africa's run-down inner cities.
Medics stand by the covered bodies of victims of a deadly blaze in downtown Johannesburg. AP
Arson was suspected, but the latest details on what may have happened only surfaced when the suspect, apparently wracked with guilt, came forward this week.
According to Andy Chinnah, a rights activist with Amnesty International who was present at the enquiry, the suspect confessed to being a drug user who had befriended a dealer in the building.
He helped "knock people up" if they had a problem with the gang boss, in a room called the "slaghuis" or "butchery" where victims were tied to a chair and beaten.
On the day of the fire, Chinnah said, when the suspect "pulled the sack off the victim's head he noticed that the guy was someone he knew."
High on drugs, and fearing that he would be identified, the suspect strangled his victim and then went to a nearby petrol station to buy fuel, before dousing the body and setting it alight.
"As he stood outside and watched the building burn, he said, he saw a child being thrown out from the fourth floor and a woman jumping," Chinnah said.
"He said he then realised what he had done was much bigger than what he intended."
Eventually the fire-starter decided to come to the inquiry to confess, said the activist, who has also been briefed by lawyers for the victims.
A police spokesman said the new suspect would appear in court "soon" on charges of arson, 77 counts of murder and 120 counts of attempted murder.
After the fire, bodies - many "burnt beyond recognition" - were discovered piled up at a security gate that was closed, preventing people from escaping the blaze.
Agence France-Presse