The investigation into former security czar and member of the Politburo's all-powerful Standing Committee, Zhou Yongkang, makes him the most senior victim yet of president Xi Jinping's anti-corruption crackdown.
Rumours are circulating that the probe may be widened to include the death of his ex-wife Wang Shuhua, who was killed in a road accident in 2000, shortly after she had split from her husband.
Reuters cited a source this week with direct knowledge of the probe saying investigators were looking for evidence of foul play involving Mr Zhou (71) in the crash. Mr Xi has waged a campaign against corruption, which some say is focused on particular rival factions within the party, since he assumed control of the main offices of the party in late 2012.
No public charges
Beyond a short statement in July from the Central Commission for Discipline Inspection saying Mr Zhou was officially under investigation, there has been no public information about the probe and he has not faced any public charges. Any information is generally based on rumours and leaks.
The corruption probe is stepping up a gear, probably ahead of the Communist Party's fourth plenary session in October, which is expected to discuss the progress made on the effort to squeeze graft, long seen as a threat to single-party rule in China.
There is a big question mark over whether the party is prepared to have potentially destabilising details about faction fights and elite power struggles aired at such a high-profile meeting.
China's top judge, Zhou Qiang, who is president of the Supreme People's Court, said last month the investigation into Mr Zhou showed no one was above the law.
“Leading cadres, irrespective of position or party standing and tenure, will be subject to party discipline constraints and must receive education and supervision of party organisations,” he said.
Criminal charges
Insiders say the investigation into Mr Zhou is part of a broader power struggle between factions within the senior leadership and that leaders are deciding whether to oust him quietly or allow him to face criminal charges in public like
Bo Xilai
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The rumours surrounding Mr Zhou tend to focus on him allegedly using cars to achieve his ends, almost like a developing theme. When the son of Ling Jihua, a senior party official and ally of former president Hu Jintao, was killed in a car crash while driving a Ferrari, there were whispers Mr Zhou was involved.*
And rumours of an attempted coup shortly before Mr Xi took over as president focused on Mr Zhou because one of the speculated stories said Mr Xi’s convoy had been surrounded by cars from a rival faction.
It is also said that Dai Haibo, vice deputy of the Shanghai Free Trade Zone, is under investigation, which means another high-profile cadre falling foul of the widespread crackdown.
*This article was amended on September 16th 2014
