Chinese police detained prominent rights lawyer Xie Yanyi at the weekend, as he was investigating the sudden death of disabled petitioner Guo Hongwei in a prison in the northeastern province of Jilin.

Xie was carrying out research at the home of Guo's parents in Jilin's Siping city on Saturday when dozens of police burst in and detained him, he told RFA on Monday.

"Dozens of policemen broke into the apartment and grabbed me, taking me away to Ping'an police station," Xie said. "Then they confiscated my luggage, bag and phone, rifling through my things at will."

Xie told them they didn't have a warrant, and no legal basis for conducting a search, but they took away a large number of documents linked to Guo's trial, appeal, and subsequent complaints filed by his family, who regard his death as suspicious.

"They took away the case materials linked to Guo Hongwei's cases illegally; they just stole them, all of the files, all of the evidence," he said. "They also tried to lie to me, saying they hadn't done this."

Xie was forcibly escorted aboard a high-speed train and brought back to Beijing, where he is based, he said.

He said he was investigating Guo's family's concerns about their son's death because there was a lack of transparency on the part of the authorities.

"[One possibility is that] Guo Hongwei suffered some kind of direct harm [leading to his death]," Xie said. "Another is that he was refused necessary medical treatment for something."

"And then there is a third possibility, that he died unexpectedly due to some kind of medical condition," he said. "None of these can be ruled out."

Xie called on the authorities to share the full details surrounding Guo's death.

"It's the responsibility of every citizen to demand the truth, otherwise what happened to Guo Hongwei could happen to any of us," he said.

Cover-up suspected

Guo's father Guo Yinqi said the repeated refusal of the authorities to release any information about his son's death suggests they are covering something up.

"Why did they kidnap the lawyer and confiscate all of our evidence?" Guo Yinqi said. "Guo Hongwei's body is still in the funeral home, in cold storage."

Guo died on April 9 after surgery after undergoing two operations for cerebral hemorrhage on April 4 and 5.

His death came as he was serving a 13-year jail term in Jilin's Gongzhuling Prison, where he was transferred after his family complained that he was being tortured at Songyuan Prison.

The family was prevented from taking photos of his body when they went to identify it, and doubts remain around the refusal of prison authorities to order medical parole for Guo despite his systolic blood pressure readings of around 260 consistently during the last two years of his life.

While there was no indication of external, physical attacks on Guo's body, the family has called for a full investigation into his death to establish responsibility, including the release of medical imaging from the time of the surgery and surveillance camera footage.

The family has said Guo was tortured and held in solitary confinement in a tiny cell with no light or toilet facility during much of his time at Songyuan Ningjiang Prison in Jilin.

In May 2020, prison guard Lu Jiaxun locked him in a cell filled with peracetic acid, causing him choke, they said, yet the guard only received a small deduction from his bonus as punishment.

Guo Yinqi filed a complaint to the Jilin provincial prison administration bureau at the time of that incident, but has yet to receive a response.

Guo was transferred to Gongzhuling Prison on Nov. 26, 2020 where he was held incommunicado, with authorities citing pandemic restrictions as the reason for the ban on visits. However, phone calls weren't permitted either.

When he was finally admitted to the Jilin Guowen Hospital in early April, police told one of the surgeons operating on him that the previously healthy Guo had been in a similar condition for more than two months. He was already in a coma at the time of admission.