Former Chongqing Party chief, Sun Zhengcai, is being investigated on suspicion of taking bribes, China's Supreme People's Procuratorate (SPP) said on Monday.
Sun is now subject to "coercive measures" and a legal case is underway, the SPP said in a statement.
Coercive measures can include summons by force, residential surveillance, detention or arrest.
Sun had been the secretary of the Chongqing municipal committee of the Communist Party of China (CPC) in southwest China since November 2012. He was removed from the post on July 15, 2017, after coming under suspicion of violating CPC codes of conduct.