Mr Heywood, 41, a businessman based in Beijing who had close links with the Bo family, was found dead last November in a hotel room in Chongqing.
It was initially claimed he had died of alcohol poisoning but on Tuesday the Chinese government said Gu Kailai, the wife of the city's Communist party chief Bo Xilai, was "highly suspected" of having murdered him.
New reports say a fearful Mr Heywood had been summoned at short notice to a meeting in Chongqing in early November with people working for the Bo family.
He told a friend he was "in trouble". After flying to Chongqing he tried and failed to telephone his contacts in the city. He was left to wait alone in his hotel room. What happened to him next is unclear.
Mr Heywood had told friends he had left documents detailing the wealthy Bo family's overseas investments with his lawyer in Britain as an 'insurance policy' in case anything happened to him, the Wall Street Journal reported.