Project GAMMA Project GAMMA was the name given to Detachment B - 57 , Company E ( Special Operations ) , 5th Special Forces Group ( Airborne ) , 1st Special Forces , U . S . Army in Vietnam from 1966 to 1970 . It was responsible for covert intelligence collection operations in Cambodia . History . Detachment B - 57 arrived in Vietnam in June 1967 . On 26 February 1968 it was moved from Saigon to Nha Trang and it received the designation Project GAMMA on 1 April 1968 , in conjunction with other special forces units such as Project DELTA ( Detachment B - 52 ) and Project SIGMA ( Detachment B - 56 ) , both responsible for Special Recon . Members of the detachment operated from nine sites under the cover of civil affairs and psychological operations offices . Project Gamma was responsible for obtaining intelligence on Cambodian support for the activities of both regular and irregular units of the Vietnam People ' s Army , as well as irregular camps in Cambodia . The top intelligence officer on General Abrams ' staff stated in October 1968 that Project GAMMA was providing 65 percent of the known data on NVA base camps and strengths in Cambodia , as well as 75 percent of the same data on South Vietnam . According to historian Shelby Stanton , by early 1969 Detachment B - 57 " had developed into the finest and most productive intelligence - collection operation the United States had in Southeast Asia " . Stanton attributes this success to the South Vietnamese authorities not being aware of operations conducted by the detachment ' s indigenous agents . According to some sources , GAMMA was also responsible for intelligence operation against Prince Norodom Sihanouk . Capture , interrogation , and killing of Chu Van Thai Khac . In early 1969 some of Detachment B - 57 ' s sources of information started to disappear . This led the detachment ' s leadership to conclude that its intelligence agents had been compromised . In the spring of 1969 a reconnaissance detachment operating in Cambodia captured photos showing Chu Van Thai Khac ( AKA Thai Khac Chuyen ) , a South Vietnamese GAMMA agent , meeting with North Vietnamese intelligence officers . Chuyen was subsequently arrested and interrogated for ten days , with polygraph tests indicating that he had compromised security arrangements and was working with the Viet Cong . Various ways of dealing with Chuyen were discussed within Detachment B - 57 , including possibly killing him . While the 5th Special Forces Group ' s executive officer strongly opposed killing Chuyen , the detachment ' s commander and operations officer met with the CIA headquarters in Saigon who suggested that " elimination . . . might be the best course of action " . On 20 June 1969 , three officers assigned to Project GAMMA drugged Chuyen , took him out on a boat into Nha Trang Bay , shot him twice in the head and dumped his body into the South China Sea . A cover story claiming that Chuyen had been sent on a one - way mission as a test of his loyalty was later approved by the 5th Special Forces Group ' s commander , Colonel Robert B . Rheault . Later , Sergeant Alvin Smith , Chuyen ' s former handler , became concerned for his safety and sought sanctuary with the CIA in Nha Trang where he revealed that Chuyen had been killed . General Abrams heard of the matter and ordered the arrest of Smith and seven involved officers , including Colonel Rheault . The case went to trial and was covered extensively by the media , and led to popular knowledge of the term " terminate with extreme prejudice " as a euphemism for " execute " . The Army defense lawyers for the eight soldiers called General Abrams and CIA officials to the witness stand . Both declined to get involved in the proceedings and testify . Finally in September 1969 , Secretary of the Army Stanley Resor announced to all that all charges would be dropped against the eight soldiers since the CIA , in the interests of national security , had refused to make its personnel available as witnesses , therefore making any manner of a fair trial impossible . Project GAMMA was deactivated on 31 March 1970 . An official Army history of the Green Berets , published after the Vietnam War , does not mention Project GAMMA or Detachment B - 57 . Although the Pentagon has declassified much material about Green Beret crossborder operations inside Laos and Cambodia , nothing on Project Gamma has been made available . Organization . Project Gamma used members of the Khmer Serei and the Khmer Kampuchean Krom in its activities inside Cambodia . It consisted of five collection teams supervising 13 nets with 98 indigenous agents . A listing of the personnel assigned to Detachment B57 " GAMMA " is available from Radix Press Houston , Texas .