Although charges were not announced, Zhou, 71 -- who retired from the Politburo Standing Committee in 2012 -- acquired a large amount of influence in government service in southwest China's Sichuan province, while his family amassed wealth in the oil and gas sector of the economy he administered. Assets valued at over 1 billion renminbi, or about $160 million, are held by Zhou's relatives, a recent New York Times investigation indicated.
The China National Petroleum Corp. -- China's largest oil and gas conglomerate -- has already been the target of graft investigations, as has the country's police and civilian intelligence services. During his career, Zhou was influential in each of these sectors.
The state news agency Xinhua gave few details of the detention, saying only the party "decided to establish an investigation of Zhou Yongkang for grave violations of discipline."