Five men linked to controversial Hong Kong publisher Mighty Current have gone missing in the past six months, sparking fears that they were seized by Chinese authorities. Chinese authorities have since confirmed that four of them are in detention. The fifth, Lee Bo, said in an interview that he was voluntarily assisting in an investigation.

Lee Bo is a major shareholder in Causeway Bay Books, which is owned by Mighty Current, and disappeared from Hong Kong at the end of the December. He is a British passport holder. In a television interview aired February 29, he said he had sneaked across the border to mainland China to help assist in an investigation.

Gui Minhai, the owner of Hong Kong publisher Mighty Current, is a Swedish passport holder. He was last seen in Thailand on October 17, driving out of a condominium complex in the resort town of Pattaya, where he owns an apartment. Thai police told CNN they have no record of Gui leaving the country. Three months later, Gui appeared weeping on state television in China. He claimed he returned to the country of his birth to turn himself in to police for breaking parole after a drunk driving accident thirteen years ago.

Lam Wing-Kee, manager of Causeway Bay Books, went missing last year while in China. A statement from the Hong Kong government on February 4 said Lam, along with colleagues Lui Por and Cheung Chi Ping, was under investigation and being held by police in Guangdong province. In an interview aired February 28, Lam, Lui, Cheung and Gui admitted to illegal book trading.

Cheung Chi Ping is the business manager of Mighty Current. China's foreign ministry spokesperson said that Cheung and his colleagues "admitted their crimes while being interviewed on television." Hong Kong police said he returned to Hong Kong March 6, refused police assistance and declined to disclose any details.

Lui Por is the general manager of Mighty Current. Like the others, he confessed to "illegal book trading" in the televised interview. It's not clear whether they were speaking under duress. Hong Kong police said Lui returned to Hong Kong March 4.