The two missing booksellers who were allowed by mainland authorities to return to Hong Kong on separate days last week both quietly crossed the border back to the mainland hours later, sources have told the Post . That was soon after they both asked Hong Kong police to drop their “missing person” cases. The mystery deepened yesterday, even as it looked like the end the road for Causeway Bay Books, the store at the centre of the storm. Woo Chih-wai, who worked at the shop until five of his associates disappeared last year, quoted bookseller Lee Po’s wife, Sophie Choi Ka-ping, as saying she was willing to give up the store in May. Lui Por came back to Hong Kong on Friday, followed by Cheung Chi-ping on Sunday. Both surfaced on the mainland after disappearing last year, accused of delivering banned books across the border on the instructions of associate Gui Minhai. They raised eyebrows by declaring they did not need any help from the Hong Kong government or police. Yesterday, a source with knowledge of the case said the two crossed the border back to the mainland the same day they returned to Hong Kong. In a brief meeting with police at the Lo Wu checkpoint, Cheung told immigration officers he was in a hurry, the source added. Cheung refused to do a formal interview with police and give an official statement. Dissident poet Bei Ling also quoted family members and former employers of Cheung and Lui as saying the two returned to the mainland the same day they came back to Hong Kong. “Their return to Hong Kong was only to tell police to drop the case on them, nothing else,” the president of the Independent Chinese PEN Centre said. “They returned to Shenzhen in a hurry, probably because that’s where they have to be on bail. Besides, that’s where their families are.” Five people from Mighty Current publishing house and Causeway Bay Books vanished under mysterious circumstances last year. Gui disappeared in Pattaya, Thailand, in October, followed by Lui, Cheung and Lam Wing-kee who went missing while on the mainland the same month. Lee Po vanished from Hong Kong in December. Their disappearances sparked widespread fears they were kidnapped by mainland agents, as they specialised in books critical of the Chinese Communist Party. Yesterday, Woo said Lee had signed an agreement with a man surnamed Chan on November 13. Under the agreement, Chan would bear the operating costs of the bookstore, cover the HK$39,000 monthly rent and run it for six months until May 13. Lee signed it because he needed someone to bear the costs as the store was losing HK$20,000 a month, Woo said. After Lee disappeared, there were 100,000 banned books left in the company’s Chai Wan warehouse. Choi had once agreed to sell the books to the Hong Kong Alliance in Support of Patriotic Democratic Movements of China. She later backed out and said she would rather throw them away, Woo recalled. “Sophie said as long as Lee Po can come back, she is willing to give up everything. She doesn’t want the warehouse or the bookstore,” Woo said. Alliance deputy chairman, Richard Tsoi Yiu-cheong, said his group had only taken about 500 books from the store. The alliance was in touch with people who were willing to buy more of the books for HK$10 each, Tsoi said. Choi initially agreed but later decided not to do so, Tsoi confirmed.