Forward Operating Base Delhi massacre are murders that occurred on August 10, 2012 at the Forward Operating Base Delhi within Garmsir village, Helmand Province, Afghanistan. A young man, who had been allowed to live on the base, killed three unarmed US Marines and one marine was also severely injured. Using only the above description and what you know about the world, "The killer of the US Marines was not a US Marine, himself." is definitely correct, incorrect, or inconclusive? 