Rarely is an image of the actual moment of death captured and preserved. When it is, as in the famous photographs of President John F Kennedy's assassination or of the summary execution of a Viet Cong officer by a South Vietnamese police chief,4 it is haunting. Even photographs of the moment before sudden death have great power-whether death is totally unexpected (as in a photograph of Luis Donaldo Colosio campaigning for the presidency of Mexico just before his assassination'), planned (as in a photograph of a man bound in an electric chair awaiting execution6 ), or in doubt and anticipated with dread (as in the photograph of a South African white supremacist pleading for his life shortly before being shot to death by a black police officer in Mmbatho, South Africa7). To some extent the photograph itself might tell us what is about to happen; to some extent we might need extrinsic information to understand the full story.' In either case, forward-looking knowledge is the principal source of the photograph's power.
Friedman, Richard D. "Still Photographs in the Flow of Time." Review of Evidence, by L. Sante. Yale J. L. & Human. 7, no. 1 (1995): 243-65.