Previously missing Hong Kong bookseller Lam Wing-kee holds a news conference with local lawmaker Albert Ho at the Legislative Council in Hong Kong on June 16. (AFP/Getty Images)

For seven days a week, 24 hours a day for five months, Lam Wing-kee was confined to a small room, under constant surveillance by rotating teams of guards. When he brushed his teeth, a guard held a piece of nylon string attached to one end of the toothbrush — just to make sure, he says, that he didn’t try to commit suicide by swallowing it.

He was forced to sign away his rights to legal representation or to see his family, he told the press Thursday, and coerced into a closely scripted televised confession.

The Hong Kong bookseller’s dramatic tale of abduction and psychological torture by Chinese authorities may have only confirmed what everyone already suspected, but the details have still horrified many people in Hong Kong.

They have also underlined concerns for a colleague, Sweden’s Gui Minhai, who vanished from his apartment in the Thai resort of Pattaya last October and has not been heard of for four months.

The men were among five booksellers who vanished last year from China, Hong Kong and Thailand, before surfacing in Chinese custody amid an investigation into their publishing business. Lam said he was detained by Chinese “special forces” on his way to visit his girlfriend in the southern city of Shenzhen on Oct. 24, news agencies reported, then blindfolded and handcuffed as he was taken by train to the eastern city of Ningbo, where he was interrogated 20 or 30 times.

Many of the books published by Causeway Bay Books, notably gossipy accounts of the private lives of senior Communist Party figures, are banned in mainland China, but were eagerly snapped up by Chinese tourists in Hong Kong — to Beijing’s rising annoyance. Lam said he and his girlfriend were accused of mailing banned books into China.

In the former British territory, many lawmakers believe the abductions have dramatically undermined their cherished freedoms and shown China’s “one country, two systems” pledge to be hollow. They have also raised concerns all over the world.

Several dozen members of a pro-democracy party founded by the student leaders of the 2014 Umbrella Revolution protests gathered outside a Chinese government office in Hong Kong Friday, news agencies reported.

Lam said his colleague Lee Po, also known as Lee Bo, had confirmed to him that he had been abducted by Chinese agents from Hong Kong itself, something that would directly contravene the “one country, two systems” pledge.

It is a claim that Lee himself publicly denies, but most Hong Kongers believe to be true.

Emily Lau, a pro-democracy lawmaker, applauded Lam’s bravery for deciding to speak out against his treatment, and expressed concerns for his safety. She called his treatment “quite horrific.”

“It shows how in the mainland there is nothing but complete lawlessness,” she said. “If China wants to join the international community as a respected member, it must abide by the code of behavior of the civilized world.”

Anson Chan, a former chief secretary of Hong Kong, said no one had believed the “absurd fiction” that the booksellers were voluntarily helping Chinese authorities with an investigation. “It is nevertheless chilling to hear the truth at firsthand,” she said. “We now have confirmation of what we always suspected: We are all vulnerable to arbitrary arrest by Mainland operatives, even in Hong Kong, and we cannot expect any help or protection from our own local authorities.”

Amnesty International said Lam’s account has helped to “expose the Chinese authorities’ lies.”

“Lam Wing-kee has blown apart the Chinese authorities’ story,” said Mabel Au, director of Amnesty International Hong Kong. “The Chinese authorities must come clean and admit the truth. The plight of the other booksellers still in mainland China is extremely worrying. They must be granted access to lawyers and where appropriate consular assistance.”

Gui Minhai’s daughter, Angela Gui, testified before Congress about her father’s disappearance in May. Speaking to CNN on Thursday, she said that she hoped that after Lam’s release, she would soon have positive news about her father.

“It makes me feel very worried because it’s been eight months and I still haven’t had any official confirmation that he is in detention,” she said.

The Swedish Embassy in Beijing was last granted access to Gui on Feb. 24 and says it has repeatedly requested a new meeting — to no avail.

“The information surrounding the disappearances of Gui Minhai’s colleagues, including recent developments, is alarming,” said an embassy spokesperson who was not authorized to be named. “Our efforts to reach clarity in what has happened to, and is happening to, Swedish citizen Gui Minhai continue unabated.”

In January, Gui briefly surfaced on Chinese television, making a bizarre televised confession in which he claimed he had returned voluntarily to China to surrender over an 11-year-old drunken driving case.

In a statement to the South China Morning Post, Sen. Marco Rubio (R-Fla.) and Rep. Christopher H. Smith (R-N.J.), who jointly chair the Congressional-Executive Commission on China, said Lam’s account may have only confirmed what was widely suspected but was nonetheless important.

“These abductions were illegal and have serious economic and security implications and call into question the future viability of the ‘one country, two systems’ model,” they said. “The charade must end and Gui Minhai should immediately be allowed to return to Hong Kong and his family.”

On Friday, Britain said it was also “deeply concerned” by the treatment of Lee, calling his “involuntary removal” from Hong Kong to the mainland a serious breach of the agreement reached with China at the time of the 1997 handover of Hong Kong.

“We continue to call for Lee’s liberty to be fully restored. We have offered support and remain ready to discuss his case with him,” said a Foreign Office spokesperson who was not authorized to be named.

Lam said he had only been allowed back into Hong Kong to collect a list of his bookstore's Chinese customers and was expected to return to the mainland — something he now does not intend to do. He said he was worried about his girlfriend's fate after he decided to speak out, but felt he had no choice.

“I also want to tell the whole world. This isn’t about me, this isn’t about a bookstore. This is about everyone,” he said. “This is the bottom line of the Hong Kong people. This is Hong Kongers’ bottom line — Hong Kongers will not bow down before brute force.”