As the Chinese public is eagerly awaiting the verdict of Bo Xilai, a former Politburo member who stood trial on corruption, embezzlement, and abuse of power charges last week, China’s anti-corruption agency is tightening its noose around a bigger “tiger.” A staunch supporter of Bo, he used to be China’s third most powerful politician.

The 70-year-old Zhou Yongkang, dubbed by overseas media as China’s security tsar, has been put under house arrest, says a source in Beijing. An investigation, led by Liu Jianhua, a female senior-level anti-corruption official, is now in full swing.  

Based on past practices, the party’s anti-corruption agency typically nabs top aides and underlings first before capturing the primary target. So far, many of Zhou’s protégés and confidantes have been detained for questioning.

On Sunday, the Chinese state media disclosed that Jiang Jiemin, who oversaw state-own enterprises and worked under Zhou at the state oil and gas industry for years, is now being probed for "serious disciplinary violations.” Jiang allegedly used public money to silence two young women who were severely injured last November during an accident caused by the son of a senior official.

Jiang’s investigation follows the recent detention of six other Zhou protégés at China National Petroleum Corp, the country’s largest oil and gas producer. In addition, party investigators also detained several of Zhou’s allies in December 2012, including the deputy Party chief of Sichuan, who allegedly facilitated Zhou’s family investments in the oil and construction businesses in the province.

Speculations about a possible investigation into Zhou and his family began circulating on the internet months ago. In February 2012, when Wang Lijun, the former Chongqing police chief, entered the U.S. Consulate to seek political asylum, Zhou allegedly urged Bo Xilai, the then Chongqing party chief, to “get Wang out at any cost.” As a result, Bo sent several hundred armed police to surround the U.S. Consulate, attempting to kidnap Wang. Under Zhou’s instructions, Bo subsequently lied about Wang’s asylum-seeking to the pubic by claiming that Wang was getting “vacation-style medical treatment.” 

In April 2012, Zhou opposed the move by senior leadership to detain Bo for his wife’s involvement in the death of Neil Heywood, a British businessman, and openly defended Bo on multiple occasions. According to overseas Chinese media reports, Zhou had hoped to pass the baton to Bo, whose experience in running a police state was second to none in the country and schemed with Bo to seize power from President Xi Jinping.  

Between 2007 and 2012, Zhou chaired the Central Political and Legislative Commission, which aims to enhance the Party’s control over the country’s legislative, law enforcement, and judicial functions. Zhou reportedly supervised a staff of 10 million – China has a standing army of 2.5 million troops – and his annual budget reached as high as $120 billion. Zhou’s expanding empire, known as China’s fourth power, besides the Party, the government, and the military, encompassed the nation’s police, the state agency for prosecution and criminal investigation, the courts, justice departments, civil affairs agencies that register non-governmental organizations, and national intelligence departments.

More important, Zhou controlled the country’s large contingent of armed police, a paramilitary of former soldiers, specifically charged with handling social unrest.  Under Zhou, armed police were used to suppress pro-independence protests in Tibet and persecute Falun Gong practitioners, Christian underground church members, political dissidents, and to arbitrarily arrest and torture petitioners and human rights lawyers. In recent years, the commission has allowed police to take extreme measures, such as kidnapping, torture, and illegal confiscation of personal property without having to justify their actions. The judiciary passively condones the practice. Human rights activists accused Zhou of turning the country into a de facto police state.

“It’s been a tradition in Chinese politics that every new leader cages a couple of ‘big tigers’ at the beginning of their reign,” says an analyst.

Overseas Chinese media, quoting Beijing insiders, reported in April 2012 that Zhou was a womanizer and followed the steps of his idol, J. Edgar Hoover by ordering his staff to secretly monitor the telephone conversations of senior leaders and establish files on them. Enraged by such reports, Zhou ordered multiple hacker attacks against key Chinese language media websites abroad last year.

Prior to his tenure at the commission, Zhou spent most of his career in China’s oil industry and for six years headed China National Petroleum Corp, which manages oil and natural gas exploration and production in China and some 30 countries. With China’s growing appetite for oil and other energy resources, Zhou ignored international criticism and visited Sudan fourteen times to cement ties with its corrupt and genocidal government, critics say.

China’s state monopoly of the oil industry, with an unlimited budget, is a breeding ground for corruption. A number of officials have been convicted of corruptions and embezzlement in recent years, including the chair of China National Petroleum Corp. According to overseas Chinese-language media, Zhou’s son used his father's influence to pocket billions of dollars from investments in the oil businesses. His family currently holds real estate and investment assets in China, France, the United States, and Switzerland.

Boxun, a U.S. based online news services, reported that Zhou’s son also extorted “protection” fees and in one instance lobbied to get a key triad leader released from jail after accepting $3.3 million in bribes. 

Since Zhou’s retirement last November, his power base has diminished. In the new leadership makeup, the status of the Central Political and Legislative Commission was downgraded. His successor no longer holds a seat at the Politburo Standing Committee, thus restricting, to a certain extent, the unchecked power of this gigantic state machine.

Up until last week, many analysts believed Zhou would survive. “For the sake of collective unity, members of the Politburo Standing Committee have been granted immunity from criminal investigations and prosecution,” commented Gao Yu, a Beijing-based journalist. Gao cited a consensual rule made in the 1980s among Party veterans to exempt senior members from purges in an effort to preserve the stability of the Party. That explained why Zhou was allowed to serve out his five-year term last year.

“It’s different this time because (President) Xi Jinping is under tremendous pressure to break the unwritten rule,” a senior official in Beijing said during an interview Sunday. 

While the moves against Zhou and his friends are seen as an extended attempt to further purge Bo’s former allies, the official said they will enable the leadership to reorganize China’s oil industry, where rampant corruption has been blamed for causing China’s rising oil prices and deteriorating environment, and to restructure China’s judicial system, whose power was widely believed to have been severely eroded under Zhou. President Xi reportedly plans to boost judicial independence by putting the court in the hands of a committee within the central Party apparatus to reduced local interference.

To the majority of Chinese, the news is hardly surprising. “It’s been a tradition in Chinese politics that every new leader cages a couple of ‘big tigers’ at the beginning of their reign,” says an analyst on the Chinese language website, Boxun. “Putting high-ranking official on trial illustrates the new leader’s guts to stem corruption while ridding himself of a fierce political opponent.”

At present, Zhou’s future faces uncertainty. The son has left China and his current whereabouts are unknown. There is no way to know whether Zhou will be handed over to the court like Bo Xilai or he’ll simply get internal rebuke. In the short time, the investigation of Zhou, whose stories of corruption are well-known among the Party inner circles, will no doubt add credibility to the party’s promise to capture both low-level "flies" and high-ranking "tigers,” all of whom, says President Xi, are threatening the survival of the Party’s rule.