Photojournalist Eddie Adams captured one of the most famous images of the Vietnam War - the very instant of an execution during the chaos of the Tet Offensive. It would bring him a lifetime of glory, but as James Jeffrey writes, also of sorrow.
Warning: This story includes Adams' photo of the moment of the shooting, and graphic descriptions of it.
The snub-nosed pistol is already recoiling in the man's outstretched arm as the prisoner's face contorts from the force of a bullet entering his skull.
To the left of the frame, a watching soldier seems to be grimacing in shock.
It's hard to not feel the same repulsion, and guilt, with the knowledge one is looking at the precise moment of death.
Ballistic experts say the picture - which became known as Saigon Execution - shows the microsecond the bullet entered the man's head.
