Image copyright AFP Image caption China's biggest film star and the president of Interpol both recently vanished - before turning up in detention

The recent disappearances of two high-profile Chinese citizens have once again focused international attention on China's legal system and its use of secret detentions.

First to vanish was A-list actress Fan Bingbing, who appeared in the X-Men and Iron Man film franchises.

She was not seen in public for months over the summer and went silent on social media, before turning up in early October with a grovelling apology for evading taxes.

Two days after she re-appeared, it emerged that the president of global policing agency Interpol, Meng Hongwei, had disappeared on a trip to China. His wife says his last communication with her was a text with a knife emoji, which she took to mean he was in danger.

On 8 October, Chinese authorities announced he was being investigated for bribe-taking.

While these two cases have triggered a wave of international attention, forced disappearances are nothing new in China.

Disappearance, confession, sentence

But these latest instances "show just how fundamental such enforced disappearances have become to governance in China under President Xi", says Michael Caster, a researcher and author of The People's Republic of the Disappeared.

Typically, he says, the scenario plays out like this:

The individual disappears and it takes days or weeks until there's word from authorities confirming that the person is being held and what they're accused of

Eventually, there's a public confession and apology - although some people remain detained for years without any news emerging

Usually there will be some form of further detention or jail time to serve - Fan Bingbing was instead hit with a massive fine of $129m (£99m).

Media playback is unsupported on your device Media caption Meng Hongwei's wife shares husband's final "knife emoji" text

The disappearances can target people from different walks of life: human rights lawyers, corrupt officials, officials who are targeted for political reasons, book-sellers who publish material that angers party leaders, or prominent people who fall foul of the party for one reason or another.

China's rules always rule

Since Xi Jinping took over as China's top leader in 2012, the space for dissent in China has shrunk - and activists say the crackdown is getting tougher and more systematic.

President Xi's anti-corruption drive has disciplined more than a million officials since 2012. Critics have long accused the government of using the highly popular campaign as a political tool to target rivals.

From a domestic perspective, far more prominent figures - politically speaking - than Ms Fan or Mr Meng have been ensnared.

The most senior official targeted so far is Zhou Yongkang, once the third most powerful politician in China and the overseer of domestic security. In 2015 he was jailed for life for bribery, abuse of power and disclosing state secrets.

Meng Hongwei was promoted to vice-minister of public security under Zhou and Chinese officials spoke of their aim to completely "eliminate the pernicious influence of Zhou Yongkang" when announcing the allegations against Mr Meng.

This has many observers convinced the action against him is driven by politics.

But just how brazen China has been in dealing with Fan Bingbing and Meng Hongwei, both hugely prominent individuals internationally, has intrigued some China watchers.

The fact they both simply vanished for a significant period of time drew a lot more attention to their cases than a straightforward detention and announcement of an investigation would have done.

So why use this approach?

"It's the Chinese Communist Party really showing both China and the world that it sees its rules as dominant," said Isaac Stone Fish, senior fellow at the Asia Society's Center on US-China Relations.

"There's no sense they have to explain themselves or their decisions to anyone outside the system."

A domestic audience

As far as the party is concerned, however, individuals who are investigated have not "disappeared"; they are detained according to a very orchestrated and bureaucratic process.

Image copyright Reuters Image caption Xi Jinping (left) is seen as the most powerful Chinese leader since Mao Zedong (right)

Getting its officials into senior positions at international organisations, like Mr Meng at Interpol, gives China greater international influence.

But Mr Stone Fish said Mr Meng's arrest was "a clear message to international bodies like the UN, the World Bank, IMF, or IOC [International Olympic Committee] that anyone [Chinese] they appoint can be suddenly be seized with absolutely no notice".

It suggests Mr Meng was, in China's eyes, a Party member above all else.

The detentions undoubtedly hurt China's international image, says Mr Caster, but the main audience for the intended message is domestic.

Image copyright Getty Images Image caption Fan Bingbing is one of the world's highest paid actors

"It's about breaking the individual as much as breaking the community around them.

"It's very much about signalling to other members of that community. Whether that's a community of human rights lawyers or of tax-evading celebrity actors or of a political faction."

What surprised many observers is that Interpol accepted Mr Meng's resignation - seemingly issued from secret detention - without publicly questioning it.

As Mr Caster describes it: "He has issued a statement impossible to verify. And yet Interpol has just accepted this and appears not to be pushing back against it."

What happens to those who vanish?

"There are any number of really cruel practices," says Mr Caster. "Sleep deprivation, around the clock interrogation with physical abuse. People are made to stand in stress positions, there is sexual humiliation, they are beaten, punched with batons or receive electric shocks."

Media playback is unsupported on your device Media caption Chinese lawyer Xie Yanyi recounts torture under Xi's 'war on law'

It depends on the purpose of the interrogation, he adds, and may well also depend on what kind of person it is: a grassroots activist, a human rights lawyer, a high-level party official or a celebrity.

But he said it was not certain that a well-known person would necessarily be treated better. "The depth of cruelty often exceeds what people have expected."

Despite widespread allegations, the Chinese government has emphasised that it prohibits torture and has claimed to have prosecuted many "torture offenders" in state institutions.

Whatever happens in detention, those who vanish invariably reappear professing their guilt and apologising.

Fan Bingbing said she was "so ashamed of what I've done", adding: "Without the good policies of the party and the state, and without the love of the people, there would be no Fan Bingbing."

Mr Meng will almost certainly stand trial on bribery allegations, and China's conviction rate is more than 99%.

For many observers, the detentions of people like Fan Bingbing and Meng Hongwei are an indication that where Chinese citizens are involved, Beijing will set its own rules.

Despite how it may look to the wider world, loyalty to the Communist Party, and to President Xi Jinping, must come first.