The second-highest graft buster in Shanxi was detained immediately after his supervisor published an article yesterday urging the punishment of officials who objected to the leadership's anti-graft crackdown. The official announcement by the Communist Party's Central Commission for Discipline Inspection (CCDI) of the investigation into Yang Senlin, the executive deputy secretary of the provincial graft-fighting body, adds the 57-year-old to a list of officials brought down in a probe of officials with connections to the coal-rich province. Intensive investigations in the province have prompted speculation that the authorities is building a case against Ling Jihua, a Shanxi native and the key aide to former president Hu Jintao . Dozens of officials in the region have been detained for corruption, including Ling Zhengce , vice-chairman of Shanxi's political advisory body and Ling's elder brother. The South China Morning Post reported on Tuesday that Wang Jiankang, Ling's brother-in-law and a deputy mayor of Yuncheng in Shanxi, has been in custody since late June. Wang is either helping with, or is directly implicated, in a graft inquiry, three sources have said.