Yang Weize, the first provincial-level official investigated on suspicion of "serious violations of disciplines" and laws in 2015, is said to have close connections with Zhou Yongkang, the country's former security chief.
From 2004 to 2011, Yang worked as the Party chief of Wuxi, Jiangsu province, where Zhou's hometown is located and many of his relatives live, Chinese media reported.
According to Beijing Youth Daily, Yang, 53, first built contacts with Zhou's brother, Zhou Yuanqing, who was deputy director of the land resources bureau of Wuxi's Huishan district, and then was introduced to Zhou in Beijing.
Yang later stopped the demolition of Houqiao township that had jurisdiction over Zhou's hometown, Xiqiantou village. He was also said to have abused his power by colluding with Zhou's son and his other relatives, Beijing Youth Daily reported.
According to Hong Kong Commercial Daily, Yang introduced TV anchors to Zhou Yongkang and slept with the anchors himself.
On Sunday, Yang was taken to Beijing by high-speed train from Nanjing, one of themost important cities on the Yangtze River Delta. He had been the Party chief of the city since 2011.
Yang's wife and his secretary were taken away by the discipline inspection department on the same day, Chinese media reported.
His wife allegedly participated in several construction programs when Yang was mayor of Suzhou, Jiangsu province, including a viaduct that used inferior materials and had problems with its foundations.
Yang's alleged mistress, Yu Minyan, who was the director of the publicity department of Wuxi New Area, was also taken away, according to an official who did not want to be identified. The two were said tohave a daughter.
Chinese media also reported that Yang was investigated because of a report by Gao Dezheng, a former deputy governor of Jiangsu province and the father-in-law of Nanjing's former mayor Ji Jianye.
Cang Wei in Jiangsu contributed to this story.