Beijing (AFP) - When human rights lawyer Li Heping returned to his home in Beijing after a two-year incarceration, his wife did not recognise the frail white-haired man standing in her hallway.
"He is only 46 years old, but I thought he was an old man," Wang Qiaoling told AFP. "He had lost 15 kilogrammes (33 pounds) and looked completely different."
Wang, speaking on Li's behalf because she said he remains under strict police control, alleges her husband was force-fed medication and sometimes chained for long periods during his detention in the neighbouring city of Tianjin.
Best known for defending blind lawyer Chen Guangcheng, Li also represented members of the banned Falun Gong spiritual sect, environmentalists and victims of forced eviction.
The Beijing Global Law Firm partner was detained by police during the so-called "709 crackdown" in the summer of 2015, when some 200 legal staff and activists were rounded up.
He was released earlier this month after a court handed him a three-year suspended sentence following a secret trial, convicting him of inciting subversion of state power.
In a 2014 photo, Li appeared youthful with plump cheeks and jet black hair. But in a video of Li emotionally reuniting with his wife and their daughter, he looked gaunt with thinning, grey-white hair.
Shortly after his arrest, "a doctor from the police investigation team told him he needed blood pressure medicine. My husband has never had blood pressure issues and told the doctor he didn't want it, but he was forced to take the pills six days a week," Wang said.
The side effects made "his muscles hurt, his vision blurred and he had trouble thinking clearly... He was kept drugged until shortly before his release," Wang said.
She also claims Li's hands and feet were shackled together for the entire month of May in 2016, with a chain so short that he could not stand up or lie down.
"They tried many ways to coerce him to confess," she said.
Police in Beijing and Tianjin did not respond to requests for comment.
Amnesty International has noted several cases of detainees in the 709 sweep saying they were force-fed blood pressure drugs.
"It's an ill-treatment method that is difficult to investigate as the medicines would only stay in their blood for a period of time," Amnesty China researcher Patrick Poon told AFP.
Li went to a private doctor shortly after his release, who said his body was "damaged" and noted black spots on his face, Wang said.
"The doctor could not confirm if he took blood pressure medicines, because it was 10 days after he was sentenced and there couldn't have been medicine left in his blood," Wang said.
- 'Pathetic condition' -
Chinese President Xi Jinping has overseen a tightening of controls on civil society since assuming power in 2012, closing avenues for legal activism that had opened up in recent years.
"Evidence is gradually leaking out that detainees are sometimes being forced to absorb unneeded medicines and drugs that adversely affect their mental and physical capacity," said Jerome Cohen, an expert in Chinese law at New York University.
"This alleged misconduct may help explain the pathetic condition of some of the leading rights advocates victimised by the current campaign to suppress them," Cohen said.
Other allegations about the use of suspicious medicines on detainees go further back.
Yin Liping, a Falun Gong practitioner, told the US Congressional-Executive Commission on China last year that she was cuffed to a bed in a labour camp's clinic and injected with an unknown drug for over two months in the early 2000s.
Yin said she temporarily lost her vision and developed endocrine disorders, incontinence and has had blood in her urine.
Last Thursday, Wang and other wives of Chinese lawyers testified to the US Congress about their husbands' ordeals.
In a video message, Wang said Li had to sit for hours in stress positions or shackled.
"He suffered from very cruel and sick torture," she told the congressional hearing.
Beijing has an obligation under the UN Convention against Torture to impartially investigate torture allegations.
But China's politicised system "makes it very difficult for the government to set up a credible impartial investigation," said Frances Eve, researcher at the Chinese Human Rights Defenders non-governmental organisation.
Earlier this month, Xie Yang, another 709 detainee, was released on bail after pleading guilty to inciting subversion. At his trial, he recanted his claims that he was tortured.
His wife, Chen Guiqiu, told AFP she thought her husband sounded "strange" on the phone, but she is unable to verify his health condition because she and her daughters are now seeking asylum in the US.