Chinese authorities arrested former security czar after accusing him of crimes ranging from accepting bribes to leaking state secrets, state-run news agency Xinhua reported on December 5. The 71-year-old, who is now expected to stand trial, is by far the highest-ranking official so far to be caught up in Chinese President Xi Jinping's anti-corruption drive. The party's anti-graft watchdog, the Central Commission for Discipline Inspection of the Communist Party of China (CPC), had launched an official investigation back in July.

Until his retirement in 2012, Zhou was a member of the Politburo Standing Committee (PSC), the most powerful decision-making body in China. Incumbent and retired members of the body had been until recently considered off-limits for prosecution. Zhou was closely associated with convicted former Party Secretary of Chongqing, Bo Xilai.

Rebecca Liao, a corporate attorney and writer specialized in Chinese politics and culture, says in a DW interview that it is possible that we will never know exactly what state secrets were leaked. Furthermore, she adds, it is possible that Zhou may have slipped confidential information to Bo in an effort to aid him as his political career was coming to a fast end.

DW: What charges is Zhou facing?

Rebecca Liao: According to a statement released by authorities after last Friday's meeting of the Politburo, an investigation of Zhou opened in late July revealed that he had leaked state secrets, had taken massive bribes, violated Communist Party discipline, helped relatives and mistresses reap business profits off of his power and traded money and power for sex.

The Supreme People's Court announced in a separate statement that it will prosecute Zhou, but the charges are as yet unannounced. This is par for the course in these types of criminal proceedings.

You'll remember that Bo Xilai was also expelled from the party and accused of several grave crimes before formal, lesser charges were brought against him and a trial timetable set.

You mentioned that Zhou is also accused of leaking state secrets. What can you tell us about this?

It's possible we will never know exactly what state secrets Zhou leaked. The Communist Party will do everything in its power to protect this information from further public exposure, hence the general consensus that at least part of Zhou's trial will be behind closed doors.

Professor Joseph Fewsmith, an expert on China's leadership has suggested that the secrets may have to do with Bo's communications to Zhou. The two were close political allies, and Zhou may have slipped confidential information to Bo in an effort to aid him as his political career was coming to a fast end.

Is the crackdown on Zhou mainly about fighting corruption?

Behind every corruption crackdown there is some sort of political decision. That said, the main message the party wants people to take away from this is that it is sincere in its promise to go after both tigers and flies. Members of the Politburo Standing Committee were considered safe from prosecution, but no longer.

To which extent could his downfall be linked to his connections with Bo Xilai?

Zhou was Bo's closest political ally on the Politburo Standing Committee, possibly his only champion. While the rest of his colleagues were figuring out how to silence Bo's rogue campaign to ascend to the highest echelons of political power, Zhou supported him.

The expectation was that if Bo made it to the Politburo Standing Committee, he would take over Zhou's role as Secretary of the Central Political and Legal Affairs Commission. The connection with Bo could not have helped Zhou, but it is hard to conclude how much it contributed to the crackdown.

What message does Xi want to send to potential challengers?

If there were any doubts that Xi was firmly in control of the party, they have been put to rest. Zhou's former power bases - Sichuan local government, the oil industry and the state security apparatus have all publicly voiced their condemnation of corruption in the days leading up to and since Zhou's arrest.

Zhou had probably long since ceased to be a threat to Xi, but it certainly does not hurt Xi to demonstrate his authority with a significant example.

Rebecca Liao is a corporate attorney and writer based in Silicon Valley, focusing on Chinese politics and culture.