Hong Kong bookseller Lam Wing Kee may be a fugitive in the eyes of the Chinese authorities, but he is unlikely to be sent back from Hong Kong.
While Chief Executive Leung Chun Ying had refused to say what he would do if Beijing demands Mr Lam's return, legal experts agree the bookseller is safe in Hong Kong because there is no extradition agreement with China.
The case of Mr Lam, who said he had been held captive for eight months by Chinese agents, and four other Hong Kong booksellers said to have been detained for selling banned gossipy titles about China's leaders, has put a spotlight on the legally contentious area of when China or Hong Kong should have jurisdiction in cases involving cross-border crimes - given that each side has its own criminal law system.
The recent claims of abduction and interrogation by Mr Lam, who returned to Hong Kong this month, prompted outrage in the city to grow over what many deem to be the Chinese authorities taking extralegal action in breach of the "one country, two systems" framework, which allows more liberties in Hong Kong than in China.
Independent groups who want to break away from Beijing are also becoming more vocal, ahead of Hong Kong's Legislative Council elections in September.
Almost two decades after the 1997 handover from British rule, both sides have yet to iron out the processes when an act is legal in Hong Kong but illegal in China.
- How previous cross-border criminal cases were handled
HONG KONG RESIDENT CHEUNG TZE KEUNG, WHO WAS EXECUTED IN CHINA
In 1996, Chinese gangster Cheung Tze Keung masterminded separate kidnappings of Hong Kong tycoon Li Ka Shing's son Victor Li and property tycoon Walter Kwok.
Two years after the brazen crimes, in which the victims were released after short detentions, Cheung was arrested on the mainland on July 22, 1998.
Cheung and his 35 accomplices, 18 of them Hong Kong residents, faced a series of charges by Guangzhou Municipal People's Prosecutor relating to "cross-boundary crime including illegal purchasing, trafficking and storing explosives, smuggling of firearms and ammunition and kidnapping".
Despite lobbying by Cheung's lawyer, and other constitutional experts, for the trial to be transferred to Hong Kong, Cheung was tried in Guangzhou.
Media reports said he made a full confession on the first day of the trial and was sentenced to death. He appealed but lost and was executed by shooting a month later.
The prosecution of Cheung, a Hong Kong resident, by the mainland courts triggered a debate on the exercise of jurisdiction between the mainland and Hong Kong authorities.
Hong Kongers raised concerns over the Chinese authorities exercising jurisdiction over criminal activities committed in Hong Kong by Hong Kong residents.
But the Chinese government argued that even though the crimes were carried out in Hong Kong, they were planned on the mainland. Hence, the Chinese authorities had jurisdiction over the case. The authorities also cited the Chinese Criminal Code which stated that a Chinese national can be tried by a mainland court for crimes committed outside China if the offence warrants imprisonment of three years or more.
CHINESE GEOMANCER LI YUHUI, WHO WAS SENTENCED TO DEATH FOR POISONING FIVE WOMEN IN HONG KONG
On July 21, 1998, five women were killed with poison at a residential unit in Kowloon.
Li Yuhui, a resident from Shantou, was later identified as a suspect and arrested three months later by mainland police when he fled to Tongcheng, Hubei province.
A public trial was later held at the Intermediate People's Court in Shantou, where Li was charged with robbery and murder committed in Hong Kong.
He was sentenced to death in March 1999.
Li's appeal was later heard at the People's Court of Guangdong province, which upheld the death penalty and carried out the execution on the same day.
The case sparked controversy over judicial autonomy, with the mainland insisting on a trial with no objections from the Hong Kong Special Administrative Region government, although the crimes occurred in Hong Kong and involved local victims, reported the South China Morning Post.
Hong Kong's Security Bureau had said that Li was not covered under the arrangements with China that allow fugitives to be returned to Hong Kong, and under Section 7 of the Criminal Law of China, the mainland had extra-territorial jurisdiction over crimes committed by mainlanders outside its territory, reported the Post.
In theory, even if a Hong Konger commits an offence in China, the Chinese authorities cannot arrest a suspect who is based in Hong Kong, said Mr Eric Seto, partner of criminal law firm Morley Chow Seto in Hong Kong.
Noting there is only "some sort of administrative arrangement" whereby the Chinese authorities can ask Hong Kong law enforcement agencies to provide assistance, Mr Seto said "there is no legal obligation to assist".
Since the reunification with China, Hong Kong, under the Basic Law, has been authorised to negotiate its own extradition treaty with other countries.
While the city has treaties with 29 countries, including Singapore, the United States, Britain and Malaysia, it does not have a formal arrangement with China.
However, Mr Seto said that under an administrative arrangement with China, the authorities there can surrender fugitives alleged to have committed crimes in Hong Kong. But Hong Kong has never surrendered anyone escaping the Chinese police, he said.
In a recent interview with The Straits Times, Mr Lam, 61, said he was nabbed by the Chinese authorities when he crossed the border to Shenzhen last October and was held without access to a lawyer.
While it is considered an offence under Chinese law, there are no restrictions in Hong Kong on selling books banned in China, said Dr Willy Lam, adjunct professor at Chinese University of Hong Kong.
While it is unclear if Beijing has asked the Hong Kong authorities to return Mr Lam, Dr Lam said such a request would be a "blatant violation" of the "one country, two systems" framework and it would be "disastrous" for Mr Leung's administration to surrender Mr Lam to the Chinese authorities.
Asked if the Chinese authorities are allowed to carry out investigations in Hong Kong, a spokesman for Hong Kong's Security Bureau said the city's police and its Chinese counterparts can visit each other's territory for investigation purposes.
But enforcement, such as the arrest of a suspect, can be done only by local agencies.
Last week, Mr Leung said he would review the mechanism with China, saying it has "room for improvement".
Yesterday, Beijing newspaper Global Times reported that China's Ministry of Public Security said the existing mechanism, which has been in place for more than a decade, "needs to be improved".
The report also said statistics from the ministry showed 6,172 Hong Kong residents placed under "coercive measures", including residential surveillance and detention in China, were reported to Hong Kong police by the end of last year.