The timing of the knock on Jimmy Lai's door on Thursday may have been a coincidence, but hardly anyone in Hong Kong thinks it was.

The raid on the home of a media tycoon who is an outspoken supporter of Hong Kong's democracy movement by the Independent Commission Against Corruption was a message as clear as the horse's head studio boss Jack Woltz found in his bed in The Godfather.

Adding to the message, two weeks ago a pro-Beijing newspaper in Hong Kong, the Oriental Daily, published a full-page fake obituary of Lai paid for by an anonymous advertiser.

Jimmy Lai is being told to shut up, or else, as the struggle over democracy in Hong Kong comes to a head.

This weekend, the Standing Committee of the National People's Congress, China's parliament, will announce the rules for the election of Hong Kong's next leader in 2017.

According to reliable reports, only candidates approved by Beijing will be allowed to run for the post of chief executive — a slap in the face to Hong Kong's growing legion of democracy campaigners who have been demanding universal suffrage with a "genuine" choice of leadership candidates.

They are promising to respond with immediate protests leading up to a complete shutdown of Hong Kong's central business district, the economic heart of the territory.

With that in the wind, the ICAC investigation of Jimmy Lai and other prominent advocates of greater democracy feels especially ominous.

The creation of Hong Kong's most feared and respected law enforcement body in 1974 was a key factor of the transformation of a small British colony off the coast of China into a global commercial and financial powerhouse.

Jimmy Lai, chairman of Next Media, has been a rarity among Hong Kong business tycoons for being an unabashed critic of China and a staunch democracy advocate for years. (Bobby Yip / Reuters)

After cleaning up a police force known as the finest money could buy, the ICAC has used its extraordinary powers to tackle corruption, in the process allowing honest government and the rule of law to take root.

So even the suspicion that the ICAC is being used for the persecution of political enemies is a grave blow to Hong Kong's unique blend of business genius and probity.

'One country, two systems'

Ironically, the ICAC was created specifically to deal with a problem that came from the mainland.

The agency's own official history notes that the problem of corruption, which was stifling the colony, was the result of a "massive growth in population in the 1960s and '70s" through the arrival of refugees fleeing the turmoil of Mao Zedong's political campaigns across the border.

"The government, while maintaining social order and delivering the bare essentials in housing and other services, was unable to meet the insatiable needs of the swelling population," the ICAC history reads. "This provided a fertile environment for the unscrupulous."

Now, it is the ICAC that appears as if it is being used unscrupulously against those who would oppose Beijing's gradual transformation of Hong Kong into just another big city in Southern China ruled by an alliance of party hacks and billionaires.

Hong Kong has always prospered by being different from China, even after becoming part of the People's Republic when Britain handed it over 1997.

The promises then made by China of "One country, two systems" and "Hong Kong people ruling Hong Kong" have been respected for the most part — until now.

Today, instead of allowing Hong Kong to be different, China seems determined to import some of its own most serious flaws, including one-party rule and the politicization of the police and security services, and even the ICAC.

A turbulent fall

According to Nicolas Bequelin of Human Rights Watch, "The rule of law in Hong Kong has eroded faster in the past few months than it had over the whole period from 1997 to 2014." And there are probably two main reasons for this.

Consolidating his power after almost two years in office, President Xi Jinping has spoken of the need for a firmer hand with Hong Kong, partly out of concern that allowing greater democracy there might lead to demands for the same in other parts of China.

Hong Kong's current Chief Executive Leung Chun-ying formally proposed electoral reforms to Beijing in early July, although he stopped short of recommending specific changes for its next chief executive. (Bobby Yip / Reuters)

The regime has also been caught off-guard by the strength of the campaign for democracy known as Occupy Central with Love and Peace, which participated in a huge march on July 1, the anniversary of the handover.

A pro-China rally a few weeks later had a much smaller turnout, and reporters noted signs of Chinese-government organization: people arriving in fleets of buses, large numbers of Mandarin-speakers with mainland connections, and some evidence of participants being paid to attend.

While it seems clear that most people in Hong Kong favour more democracy, the reverse is true in Hong Kong's legislative council (where it will still require a two-thirds majority to change electoral laws).

In Beijing, though, there's little respect for either public opinion or legislative debate.

The head of the standing committee that sets the rules for Hong Kong's election is Zhang Dejiang, a graduate of Kim Il-sung Comprehensive University in North Korea.

In Hong Kong meanwhile, though many people took to the streets in support of democracy in July, it's not clear how many will be willing to up the ante by joining an Occupy Central protest that could bring the city (and their livelihoods) to a standstill.

The pro-Beijing camp is certainly doing its best to raise fears with dire warnings of damage to the Hong Kong economy. And the fear of serious unrest may also play its part in damping down protests.

People there are reluctant to speculate about what Beijing might do if the Hong Kong police have difficulty controlling the situation.

At the same time, the Peoples Liberation Army has been giving gentle reminders of its presence in Hong Kong by installing a giant neon sign on its main building, and this week sending a "routine" convoy of armoured vehicles through the city.

The stage is set for a turbulent fall.