Authorities found no evidence that a Marine unit was responding to an ambush last year when troops allegedly opened fire indiscriminately on Afghan civilians, killing at least 19, a Navy investigator testified Monday. But, Navy authorities did not arrive on the scene until two months later and had only an hour to look at the site of the shooting, Marine Chief Warrant Officer Robert O'Dwyer cautioned. "From a law enforcement standpoint, that's ludicrous," O'Dwyer said, adding that while one investigation later determined two civilians died and 23 were wounded, another concluded 19 died and 50 were wounded. O'Dwyer's testimony opened the second week of a Court of Inquiry, a rarely used administrative fact-finding proceeding investigating the actions of two officers involved in the shootings: Company commander Maj. Fred C. Galvin, 38, of the Kansas City area, and Capt. Vincent J. Noble, 29, of Philadelphia, a platoon leader.