Born in 1942, Zhou was secretary of the Political and Legislative Affairs Committee of the party’s Central Committee from 2007 to 2012. He spent 18 years in Liaoning province working on geophysical exploration before being promoted to mayor of Panmian city. Other positions he held include vice minister of the petroleum industry (1985-1988), minister of land and resources (1998-1999), and Sichuan party boss (1999-2002). In 2002 he became head of the Ministry of Public Security and was made a member of the Politburo’s standing committee in 2007. Zhou is an engineering graduate.
Graft connections between Zhou Yongkang secretaries picked out by media sources
Detained officials with links to former security tsar part of a network of graft, newspapers say
The media on the mainland have run extensive reports hinting at the links between several top officials under investigation for corruption and the former security tsar Zhou Yongkang.
The reports do not directly implicate Zhou, but suggest his close allies were involved in an organised web of graft.
The articles came after the government's anti-corruption watchdog announced this week that a deputy governor of Hainan, Ji Wenlin, had been accused of graft. Ji was Zhou's secretary for a decade.
Central authorities began briefing officials last month on the findings of the corruption case centred on Zhou, but the investigation has never been acknowledged publicly by the government or covered openly in the mainland media.
The graft inquiry focuses on Zhou's main powerbases throughout his career, Sichuan province, the state oil and gas industry and the country's security agencies.
The China Business Journal ran an article highlighting how Ji's career crossed with Guo Yongxiang, a former deputy governor of Sichuan. Guo is another former Zhou secretary under investigation for corruption and the newspaper hinted of a wider conspiracy.
"A 'secretary gang' falls," the article said. "As the anti-graft net continues to widen, members of the 'secretary gang' closely tied to each other have finally been caught one by one."
The website of the global edition of the People's Daily republished the China Business Journal article and said in a headline that several officials who used to be secretaries of "a certain senior official" had been placed under investigation for corruption.
The piece was removed from the website a couple of hours later.
The Beijing News published an editorial saying the investigation into Ji was part of high-level graft inquiry that went to the top of the party, but it again fell short of directly naming Zhou.
"It's no longer an individual graft case, but senior-level, systematic and organised corruption," the editorial said. The article went on to list the areas under investigation, most Zhou's former powerbases.
"A tangled corrupt network has already surfaced. It controls energy, politics and the legal system, land and resources authorities and several provincial administrative departments.''
Huanqiu.com, the Global Times's website, suggested that more arrests would come at the highest level.