Just after Valentine's Day, Chan Tong-kai strangled his pregnant girlfriend, stuffed her body in a pink suitcase and dumped it in the bushes near a Taiwanese train station.

Key points: Pro-Beijing activists argue Hong Kong will become a "haven for fugitives"

Pro-Beijing activists argue Hong Kong will become a "haven for fugitives" Extradition bill has ample political protections, proponents say

Extradition bill has ample political protections, proponents say Human Rights Watch says promises are meaningless and disingenuous

He then returned to Hong Kong, where it's unlikely he'll face justice for killing Poon Hiu-wing.

The case, laden with salacious detail and an emotional outpouring for the murdered woman's family, became a catalyst for Hong Kong's proposed extradition agreement.

It was panned as a "Trojan horse" for sweeping changes that could see alleged offenders sent to mainland China.

Hong Kong man Chan Tong-kai murdered his pregnant girlfriend Poon Hiu-Wing in Taiwan. ( Facebook )

Opponents to the bill fear dissidents could be netted on trumped-up charges and harbour a deep distrust of the ability of Chinese courts to ensure a fair trial.

Taiwan has since said it would not seek Chan's extradition if Hong Kong passes the "politically motivated" legislation, removing the premise for the amendments.

Organisers estimated that some 2 million people swept the streets of Hong Kong this month to protest against the proposed changes, and fresh protests are gearing up again this weekend, with a pro-police demonstration planned for Sunday and a pro-democracy protest to align with the July 1 anniversary of Hong Kong's handover in 1997 on Monday.

But amid the unrest over the bill which has been suspended, are there legitimate concerns within the pro-Beijing camp that criminals could be getting away with murder?

'This policy can remedy the loopholes in our law'

Demonstrations turned ugly in Hong Kong with violence between riot police and protesters. ( Reuters: Athit Perawongmetha )

Dramatic footage from the protests showed police firing tear gas and shooting rubber bullets.

But Fu Zhenzhong, president of the Defend Hong Kong Campaign, said he backed Beijing and would take part in the pro-police protest on July 30.

Fu Zhenzhong said the extradition law was needed to fix loopholes. ( Supplied )

"Most of our members are in Hong Kong. They also love China, because we are Chinese," he said.

"This policy can remedy the loopholes in our law."

He said the police force played a crucial role in maintaining order, while many of the protesters "use their freedom extremely and abuse their freedom".

"It's bad because protesters threaten the stability of society," he said.

Richard Cullen, a law professor at the University of Hong Kong, said the justification for the extradition amendments was "completely sound" adding that "the safeguards are widespread and robust".

He found it unlikely the bill would be used for political ends and said China's judicial system was "far from perfect, but it's definitely getting better".

"It's not the Maoist system that it used to be at all," he said.

'Double criminality' and getting away with murder

Riot police disperse protesters from the streets of Hong Kong with tear gas and rubber bullets. ( ABC News: Brant Cumming )

Regina Ip, chair of the pro-Beijing New People's Party and former security minister, said the extradition agreement was necessary to combat cross-border crime, such as drug trafficking, money laundering and terrorism financing.

"China has said publicly that there are at least 300 fugitives from mainland China — probably people involved in bribing senior officials or managing illicit business — hiding in Hong Kong," she said.

Former security secretary Regina Ip said human rights protections are adequate in the bill. ( Reuters: Tyrone Siu )

"It is well known these people live a life of luxury, in our six-star hotels.

"We shouldn't allow Hong Kong to be a haven for fugitives."

Ms Ip said there were adequate protections in place — including "double criminality" (meaning the offence must be recognised in both mainland China and Hong Kong) and that the punishment must be greater than seven years.

"If the purpose of the request is to punish somebody by reason of his religion, nationality, race, or political opinion, that will not be allowed," she said.

"Ultimately it's for the courts to decide. The power doesn't rest on our chief executive, let alone Beijing."

But Human Rights Watch China director Sophie Richardson said assurances the extradition bill won't be used in political cases were "absolutely meaningless".

"None of those smaller improvements address the profound problems and weaknesses and politicisation of China's legal system," she said.

"Chinese law is whatever the Chinese Government and Communist Party says it is in the moment. And there are no checks on that."

She said countries and territories without an extradition treaty can still return suspects to face trial in another jurisdiction and it was "disingenuous to suggest there are no other solutions".

'Hong Kong is an inalienable part of China'

Some protesters waved the British flag, which pro-Beijing factions described as "backwards". ( AP: Vincent Yu )

As the handover anniversary looms, the latest protests have morphed from a focus on extradition to encompass a broader existential angst.

The UK handed over Hong Kong to China on July 1 in 1997, with China promising to operate "one country, two systems" for 50 years, until 2047.

Fears of Beijing's creeping influence on Hong Kong's judicial system persist — in April, activists who took part in the 2014 Umbrella Movement were jailed. Booksellers of gossipy novels about the Chinese elite where whisked across borders in 2015.

Some protesters appeared nostalgic for British rule — a handful waved the Union Jack flag, while one held a cardboard sign reading: "The Queen made us pearl of the orient. The communists ruined it."

"That is really out of date. That is 22 years ago," Ms Ip said.

"The new reality is that Hong Kong is an inalienable part of China, and the only model that works for us is 'one country, two systems'.

"We shouldn't undermine this model by stirring up sentiments against mainland China, which is our sovereign country."

Hong Kong is caught between a British past and a Chinese future. ( ABC News: Brant Cumming )

Despite the protests being branded as "pro-democracy", political scientist Ivan Choy cast doubt on whether democracy truly exists in Hong Kong.

"Democracy is not necessarily the core value of Hong Kong," he said.

"We have never elected our own governor. But in the past, we have always had judicial independence to protect our human rights. That's our core value."

Ms Ip said the protests have gone far beyond the fugitive bill.

"They have taken on highly unwelcome overtones of inviting foreign intervention," she said.

China's Ministry of Foreign Affairs did not respond to a direct request from the ABC, but spokesman Geng Shuang has said the proposed legal changes "are purely China's internal affairs" and this week accused the UK of "blatantly interfering in Hong Kong affairs and making irresponsible remarks".

"China deplores and firmly opposes that," he said.

"We urge the UK to immediately stop interfering in Hong Kong affairs and China's internal affairs in whatever form."