For much of his career, Zhou Yongkang glided among the most influential sectors of modern China - oil, land and eventually the national police apparatus.
Much of his success can be traced to his membership of the so-called petroleum gang - top officials who began their professional lives in the industry as the nation pivoted from oil exporter to importer in the 1990s. The change benefited state-owned oil giants that have exclusive rights to import crude.
A key member was Zeng Qinghong, the former vice-president. He mentored Zhou and referred him to former president Jiang Zemin.
Zhou rose to the highest level of power - membership in the Standing Committee of the Politburo. But he exposed himself to attack by aligning himself with fallen princeling Bo Xilai - another champion of the truncheon school of policing. He was reportedly the sole member of the Standing Committee to disapprove of how the former Chongqing party chief was being handled before his sacking.
Zhou was born in 1942 in Wuxi, Jiangsu province. He studied oil exploration at the Beijing Petroleum Institute, graduated in 1966, and joined a geology team scouting for wells in Heilongjiang' s Daqing Field, then just starting production.
He remained in the industry, working in exploration and surveying, and in the 1980s became acquainted with Zeng Qinghong. Zeng was then working in the liaison office of the China National Offshore Oil Corporation and would later take up key party roles in Shanghai at a time when Jiang Zemin was serving as its mayor.
In 1985, Zhou was named vice-minister of the Petroleum Industry and stayed there until it was disbanded by the central government, who renamed it the China National Petroleum Corporation (CNPC) in 1988. Over the next decade, he rose through the ranks of the corporation to become general manager, in addition to being the party's top man at the company, before he left in 1998.
Zhou was then tapped to head the Ministry of Land Resources. The following year he was named party secretary of Sichuan province, a post he held until 2002. The resource-rich province would eventually become the power base for Zhou and his family. His son, Zhou Bin, owns an investment company and a hydraulic company there. His whereabouts are now unknown.
Widely referred to as a Jiang protégé, Zhou was elected to the 25-member Politburo in 2002. He was also appointed to the powerful post of minister of public security.
Zeng officially retired in 2008, and his ties to Zhou loosened, but the minister had consolidated his grip on power the year before by making a successful play for a coveted spot on the nine-member Politburo Standing Committee. He was also promoted to secretary of the Political and Legislative Affairs Commission of the party, which oversees internal security.
His 10-years overseeing security coincided with China's hosting of the Olympics, which saw some overseas visitors complain about delays owing to security checkpoints, but the event concluded without any significant disruptions. Within the public security world, Zhou was credited with streamlining the police structure and making the force more professional and powerful.
He also took the unprecedented step of sacking hundreds of police officers to stamp out a drinking culture, earning himself prestige within the force and the approval of top leaders. But he showed he could be ruthless in dealing with external threats to the party. His ministry tightened its grip on the Falun Gong, ethnic groups, rights activists and other "subversive forces".
Before Bo's downfall on charges of bribery, embezzlement and abuses of power, Zhou was among the few leaders to openly support his leftist campaign in Chongqing. Zhou made a last-ditch effort to support Bo before he was sacked on March 15, last year, attending a Chongqing delegation session at the annual National People's Congress on March 8, where he spoke highly of the municipality's achievements. But the support failed to turn the tide.
Zhou's growing unpopularity was underscored by a petition from a group of elderly party members in Yunnan , calling for his sacking in May last year, and an ensuing investigation by the party's central disciplinary body into possible irregularities in Zhou's career.
Speculation has been rife in recent months over Zhou's fate after several of his former aides in Sichuan fell from grace, including a former Sichuan vice-governor and ex-top aide, Guo Yongxiang.