A British investigator has accused the Chinese authorities of withholding medical attention in prison in a bid to make him confess to crimes.
Peter Humphrey and his wife Yu Yingzeng - a US citizen - were detained during a probe into corruption at pharmaceuticals giant GlaxoSmithKline. The company apologised publicly in 2013 and was fined £300 million for bribing Chinese doctors to buy its medicines.
Although the couple were not implicated in the case, they had been hired by GSK to find out more about a sex tape sent to the company's London HQ - apparently in an effort to intimidate executives.
They were convicted in a separate trial in 2014 of selling the personal data of Chinese citizens to corporate clients.
Mr Humphrey was released early on health grounds last week, and his wife was freed shortly afterwards.
Speaking to the BBC after arriving back at Heathrow, Mr Humphrey said: "I was constantly harassed in prison over signing a thing they call an admission of guilt and a statement of remorse.
"I never signed those documents because I did not admit to having committed that offence as charged.
"Therefore, that's why they tried to extort this confession by withholding medical attention for my prostate condition."
Mr Humphrey, whose company ChinaWhys specialised in assisting multinational firms dealing with allegations of internal fraud, now needs urgent medical treatment for a prostate problem that has become a tumour.