Lee Po, 65 ■ Causeway Bay Books co-owner ■ Disappeared from Hong Kong in December 2015 Lee was the last of the five to go missing. Weeks before he disappeared but after four of his associates vanished, he told the Post he had no fears for his own safety because he had no plan to cross the border. Lee later surfaced on the mainland and told Beijing-friendly media he smuggled himself out of Hong Kong to assist in an investigation involving his publishing associate Gui Minhai. His smuggling claim has baffled human rights activists and other observers, as Lee in fact possesses a home return permit. Gui Minhai, 51 ■ Mighty Current shareholder ■ Disappeared from Pattaya, Thailand, in October 2015 Gui was last seen at his home in Pattaya after a man unexpectedly came to his condominium to look for him. Gui dropped off groceries he had just bought at his apartment as soon as he saw the visitor and invited him into his car. He later appeared on state-run CCTV claiming he had surrendered to mainland authorities over a drink-driving death he allegedly caused in 2003. His disappearance triggered a diplomatic row between China and Sweden, as Gui is a naturalised Swedish citizen who was born on the mainland. Cheung Chi-ping, 32 ■ Mighty Current assistant general manager ■ Disappeared from mainland China in October 2015 Mainland authorities have accused Gui of ordering associates, including Cheung, to deliver about 4,000 banned books across the border since October 2014. Cheung has admitted to playing a role in the delivery process. He returned from the mainland on March 6 and asked Hong Kong police to drop their missing person investigation. Sources said he returned to the mainland hours after he made the request. His wife, who is pregnant, lives in the mainland. Lam Wing-kee, 61 ■ Causeway Bay Books manager ■ Disappeared from mainland China in October 2015 Of the five Causeway Bay booksellers, four are Hong Kong residents – Lam, Lee, Lui and Cheung. Lam is the only one of the four who still has not returned to Hong Kong. Political commentator Johnny Lau Yui-siu, a friend of Lam, believed he had not returned to the city because his family members were all in Hong Kong. Mainland authorities had no “hostage” in their hands, Lau added, if Lam was released. According to Lau, Lam holds the smallest role of the five in the bookstore business. Lui Por, 47 ■ Mighty Current shareholder and general manager ■ Disappeared from mainland China in October 2015 Lui has admitted to mainland media that, in order to boost Mighty Current’s business performance, he helped deliver banned books across the border per Gui’s orders. When he returned to Hong Kong earlier this month, he said he was free to travel between the city and the mainland after his release on bail. Lui asked local police to close their missing person investigation, and he refused to tell them details of the mainland’s investigation. Lui’s wife lives in the mainland.