His death is being linked to the sacking of a high flying Communist Party boss, Bo Xilai, who was in charge of the city Mr Heywood died in.
Reports allege that Mr Heywood had fallen out with Mr Bo's wife.
The official police report gave the cause of death as 'excess alcohol consumption', an assessment his family did not dispute according to the British Embassy in Beijing.
His body was cremated and there was no post mortem.
However, in February the British government made an official request for an investigation into the death.
It's thought that the police chief in Chongqing, who'd fallen out with Bo Xilai, went to the US Consulate in Chengdu, a city 200 miles away, and while there, it's reported, claimed Mr Bo's wife had something to do with the death of the British businessman.
The police chief then left the US Consulate and is now believed to be in government custody.
He had been talked out of the US officials offices, the building surrounded by police cars.
A few weeks later Bo Xilai was sacked amid a blaze of publicity and allegations of corruption. He and his wife are also thought to be under house arrest.
Neil Heywood had an extraordinary friendship with Bo Xilai. It's rare for a foreigner to be close to a Party boss. An ex-Harrovian, Neil Heywood had helped Bo's son get into Harrow.
That's a sign of how close they were. However, they later fell out. Neil had said he thought someone close to Bo was briefing against him. He had considered leaving the country as a result, but he didn't.
The friend, Tom Reed, had dinner with Neil Heywood just days before he died. These are Tom's thoughts in his own words: