Confusion was mounting on Tuesday over the whereabouts of billionaire Xiao Jianhua, who was reportedly abducted by mainland Chinese state security police from his apartment in the separate jurisdiction of Hong Kong, but whose company claims he is "recuperating overseas."
Hong Kong police have said they are investigating reports that Xiao, who was living at a luxury apartment in the Four Seasons hotel, was "kidnapped" across the border by the mainland Chinese authorities.
But Xiao's relatives have since asked for the missing persons case to be closed, local media reported.
And Xiao's Tomorrow Group—which has close links to the ruling Chinese Communist Party—tweeted twice in Xiao’s name via its WeChat social media account saying he is recuperating overseas from an unspecified illness.
However, it gave no further details and has since deleted the posts, while Xiao has yet to make an appearance anywhere in person.
Hong Kong police have since confirmed that Xiao left the city via an official immigration departure point, saying they have contacted mainland Chinese authorities for clarification.
The Financial Times quoted an unnamed person as saying that Xiao was "accosted" in his Hong Kong waterfront apartment at around 1.00 a.m. on Friday by "five or six plain-clothed Chinese public security agents," who took him to mainland China along with his bodyguards.
The Four Seasons has since handed CCTV footage of Xiao's exit from the building over to Hong Kong police, the paper said.
"It is unclear what happened inside the room where Mr. Xiao was living, but there was no scuffle in the hallway or elevator and he appeared to go with them willingly once they all left his room," the paper quoted the source as saying.
University of Hong Kong law professor Eric Cheung told RFA that Hong Kong, under the terms of the 1997 handover to Chinese rule, should be treated as a separate jurisdiction to mainland China under the "one country, two systems" principle.
"The legal systems of the two places are very different, as is the attitude to the rule of law," Cheung said. "We currently lack certain guarantees, and what's more, it looks as if certain things which should not be happening are actually being legitimized."
Cheung called on the government to check the "through train" express that runs nonstop between Hong Kong and mainland Chinese cities, to ensure nobody is taken out of the city against their will.
The confusion over Xiao's whereabouts comes after the cross-border detention of British national and Hong Kong bookseller Lee Bo.
Lee, who was taken by agents of the Chinese government from his workplace in the former British colony in December 2015, reappeared in police custody in mainland China.
Swedish national Gui Minhai, Lee's boss at the now-shuttered Causeway Bay Books, which was accused of selling "banned" titles across the internal immigration border in mainland China, was believed taken from his holiday home in Thailand in October 2015.
In total, five booksellers were detained by state security police, some during visits to mainland China.
Hong Kong lawmaker and barrister Alvin Yeung said the detention of people in Hong Kong by Chinese police is out-and-out illegal.
"This isn't cross-border law enforcement; it's cross-border law-breaking," Yeung told RFA. "Mainland law enforcement agencies have no legal basis to exercise their powers in Hong Kong."
"According to reports, Xiao Jianhua was accompanied by eight bodyguards, so we need to know if force or extreme duress was used to make Xiao Jianhua leave Hong Kong," he said.
He treated the statements reassuring the world that Xiao is fine with skepticism.
"Actually, the public statements and the family asking for the case to be closed are very similar to what happened in Lee Bo's case," he said.
Lawmaker Starry Lee, who chairs the pro-China Democratic Alliance for the Betterment and Progress of Hong Kong (DAB), agreed.
"Under the Basic Law, cross-border law enforcement is not permitted," Lee said. "The security department and the police are following the case closely, and they haven't seen any evidence that this has occurred."
"We will be taking this up with the National People's Congress [in Beijing] and calling on the central government and the Hong Kong Special Administrative Region government [to keep us updated]," she said.
Guangzhou-based author Ye Du said it is likely that Xiao is being called in by Chinese investigators as part of President Xi Jinping's anti-corruption campaign.
"The case of Xiao Jianhua has left everyone guessing about the power struggles that are going on, and about how intense the anti-corruption campaign has become," he said.
"They are wondering if these power struggles will actually result in some political changes [at the highest level]."
Reported by Goh Fung for RFA's Cantonese Service, and by Yang Fan for the Mandarin Service. Translated and edited by Luisetta Mudie.