Here is what they said:
Vietnam vets say snipers who led U.S. search-and-destroy missions were said to be "taking God's view" when they took up positions in high ground - which makes the God reference in the killer's taunting note doubly suspicious.
During the Vietnam War, some soldiers put death cards in the mouths of the slain enemy; others nailed the cards to the foreheads, and still others dropped them from the air.
Retired Lt. Col. Michael Lee who wrote a history of snipers in Vietnam said many of them used the ace of spades as a calling card because the Vietnamese considered it a death card.
Another theory that is being thrown around today is that if there are two people involved it might be that they are having a contest between them as to who can shoot better. Its Sickening if that is the case.
If the two-mkan theory is true, I like the theory that it may be two men in competition with each other to see who is the better shot. A sick and twisted game of one upmanship.