Nhung was best known for his role in the November 1963 "coup d'état" led by Minh that ousted President Ngô Đình Diệm from office. At the end of the coup, Nhung - having shot Colonel Lê Quang Tung, the loyalist commander of the Army of the Republic of Vietnam Special Forces at a grave at Tân Sơn Nhứt Air Base the day before - executed Diệm and his brother Ngô Đình Nhu. An investigation led by General Trần Văn Đôn, another coup plotter, determined that Nhung had repeatedly stabbed and shot the Ngô brothers while escorting them back to military headquarters after having arrested them. In a 1994 interview, General Nguyen Khanh recalled, "Nhu (Diem's brother) was alive when they put the knife in to take out some of the organs...the gallbladder. And in the Orient when you are a big soldier, big man-this thing is very important... They do it against Nhu when Nhu was alive... And Diem had this happen to him, and later on they kill him by pistol and rifle." It was widely believed that Minh had ordered Nhung to execute the Ngô brothers. Following Nguyễn Khánh's successful January 1964 coup against Minh's military junta, Nhung died in mysterious circumstances, the only rebel fatality in the regime change.