The fate of murder suspect Chan Tong-kai, whose case has triggered the five-month mass protests in Hong Kong, remained unclear, with Taiwan (where Chan committed the crime) and Hong Kong (where Chan is now) squabbling over the next step in prosecuting the Hong Kong native.

Chan's case in 100 words

Chan has admitted to killing his pregnant girlfriend while on holiday in Taiwan and fled home to Hong Kong the next day. He was jailed in Hong Kong on money laundering offenses stemming from his use of his dead girlfriend's credit card, as Hong Kong did not have enough evidence to prosecute him for a more serious crime he committed in Taiwan.

The 20-year-old got released from prison two weeks ago and has indicated willingness to surrender himself to Taiwan and face trial. The island refused his offer initially and later made a U-turn, seeking "inappropriate" assistance to bring Chan back from Hong Kong.

Where should he be tried?

In Taiwan.

"There is a 'territorial principle' under Hong Kong's criminal justice system, which means Hong Kong only has jurisdiction over a case if part of or the whole process of the criminal acts is taken place in the area," explained Zhang Shun, assistant researcher at the Institute of Taiwan Studies of the Chinese Academy of Social Sciences.

The whole process of Chan's criminal acts took place in Taiwan; plus, Taiwan has all the evidence, both of which make the island the only legitimate place to hold the trial.

Is it appropriate for Taiwan officials to take Chan back from Hong Kong?

No.

"This involves the problem of cross-jurisdiction law enforcement, a very special legal act, which is highly unusual," Zhang told CGTN. "Unless the two sides have some kind of very functional 'Mutual Legal Assistance' mechanism or very deep mutual trust in terms of jurisdiction."

The process of Taiwan officials "taking Chan back from Hong Kong" may sound simple, but is actually another jurisdiction conducting legal enforcement on Hong Kong's turf.

"It is very inappropriate for Taiwan to have this demand," Zhang said.

The Hong Kong SAR government also dismissed the request in the first place, calling it "a disrespect for Hong Kong's jurisdictional power and is totally unacceptable."

Is Taiwan politicizing Chan's case, amid the January election?

Yes.

Observers said politics had played a part in every move of Taiwan's decision to Chan's case, especially at this point when it's just three months ahead of the island's leadership election.

Cross-Strait tensions have mounted since Taiwan leader Tsai Ing-wen took office in 2016. the Tsai administration has refused to acknowledge the 1992 consensus, an understanding of both sides across the Taiwan Strait belong to one China.

"After Hong Kong's protest crisis broke out, the Tsai administration has been utilizing the unrest and further intensifying the anti-mainland sentiment," Zhang said.

Kelsey Broderick, China analyst at risk consultancy Eurasia Group, believes the Tsai administration could benefit "if they portray the incident as an example of the party being tough on the mainland and tough on crime," as she told CNBC in a recent interview.

"If Chan can be prosecuted in Taiwan, that will change (Taiwan's) public focus from the Hong Kong protest crisis to how Chan will be charged," Zhang further explained, "that's something the Tsai administration does not want to see."

Both Tsai and the island's interior affairs authority have publicly said that once Chan lands in Taiwan, he will be arrested but not in the form of self-surrender, which means he wouldn't be eligible for sentence reduction as voluntary surrender would do.

"Note the rhetoric of the Tsai administration here, arrested by Taiwan police officers but not Chan surrendering himself," Tang Hsiang-lung, senior Taiwan political observer, said on a program on Phoenix Television. "They are telling Chan Tong-kai, you'd better not to come here."

Zhang echoed, "it is a great step made by the 20-year-old that he is willing to surrender himself, otherwise he could just walk out the prison as 'a free man' with 'free soul.'"

When will Chan be facing trial in Taiwan?

We don't know.

Experts believe it won't happen any time soon and even may not happen at all.

"Under current situation, I'd say if Tsai Ing-wen got re-elected, he won't come. If someone from the Kuomintang party got elected, he will probably think about it. But I think he will not come," Tang predicted, "People change their minds."

"After all, he is a 20-year-old young kid. Three months are a long time; he could fear."