TITLE: A MURDER IN WARTIME AUTHOR: JEFF STEIN PUBLISHER: ST. MARTIN’S PRESS; 414 PAGES; $22.95 THE BOTTOM LINE: This is the best military morality tale since The Caine Mutiny. CAPTAIN ROBERT MARASCO, WHO pulled the trigger, said the bullet that killed Thai Khac Chuyen made the sound of a “tire puncture” and splattered “blood, skull and bits of brain” on him and the other two Green Berets in the boat. Undaunted, the trio rolled the body of the alleged North Vietnamese double agent into the murky waters off Nha Trang — and into presumed obscurity. Instead, this 1969 real-life slaying triggered a Vietnam War scandal second only to the My Lai killings, and one of infinitely more complex moral overtones. The facts appear straightforward. A Green Beret unit in Vietnam running Project Gamma, a top-secret intelligence operation that monitored the results of the secret U.S. bombing in Cambodia, discovers that Chuyen, its key agent, may be a North Vietnamese double. The agent represents a profound threat to what the Green Berets perceive as a sensitive covert White House operation. A low-level CIA official in the embassy gives a wink and a nod for termination with extreme prejudice. Colonel Robert Rheault, a Green Beret officer cut in the Ollie North mode, orders Chuyen’s death. Rheault tells Saigon that Chuyen disappeared on a spy mission, but this cover story fails to convince the colonel’s already suspicious seniors. The lie soon unravels — accelerated, in part, by General Creighton Abrams’ antipathy for the Green Berets. By early August, only six weeks after the killing, the Associated Press breaks the story: BERET CHIEF, 7 aides charged in viet killing. Author Jeff Stein, who was serving as a military intelligence officer in Vietnam when the case broke, paints an exhaustively researched and heavily documented history of the murder. But is it murder? How did Chuyen’s death differ from the hundreds of Vietnamese killed in the CIA’s Operation Phoenix? Unlike the rowdy and unprofessional soldiers at My Lai, these Green Berets were elite and disciplined troops. Can they be faulted for believing Project Gamma to be an extremely critical intelligence operation, deserving of all efforts to protect it? The eight conspirators are clearly both villain and victim. Colonel Rheault was a “can do” officer reflecting the machismo he thought John Kennedy embodied. The CIA’s signals were ambiguous. This was a war without finely drawn lines, geographic or moral. If their indictments were bizarre, so, too, was the way they were freed. President Nixon, eager to protect the secret Cambodian bombing, sought to escape blame. In a note to Henry Kissinger, Nixon wrote, “K — I think Helms should be made to take part of the rap.” The CIA chief was no more eager than Nixon to take a fall. The final act in this great morality play was anticlimactic: House Armed Services Committee chairman Mendel Rivers, desiring to protect both one of his constituents who was among the accused and the Army’s reputation, told Nixon to lay off. If the case went to trial, Rivers pledged to kill the defense money bill for that year. Army Secretary Stanley Rezor called a press conference to announce meekly that “for reasons of national security” the cases would not be prosecuted.