As colonel, he took part in the May 16 coup in 1961, when he led a group of soldiers to take Prime Minister John M. Chang into custody.

He served for two years as Minister for Home Affairs in the junta and then was director of the KCIA from March 1963 to October 1969, where he was notorious for his brutality and corruption.

His nicknames are Flying Pork Cutlet (or Flying Tonkatsu) (날으는 돈가스; Nareuneun Dongaseu), Pork Belly of Fear (공포의 삼겹살; Gongpoui Samgyeopsal),[2] and Namsan Wild Boar (남산 멧돼지; Namsan metdwaeji).

[9] A popular rumor is that Kim was smuggled back to Seoul and personally shot by President Park in the basement of the Blue House.

[a][10] In February 2005, the Monthly Chosun published claims that Kim had been lured from New Jersey to Paris by a hired female entertainer and then been kidnapped by a French criminal syndicate in pay of the South Korean government,[11] then murdered and ground up in a hammer mill which is a grinder at a chicken farm and turned into chicken feed by agents of the KCIA.