WASHINGTON — Army Sgt. La David T. Johnson died in a hail of gunfire, hit as many as 18 times as he took cover in thick brush, fighting to the end after fleeing militants who had just killed three comrades in an October ambush in Niger, The Associated Press has learned. A military investigation has concluded that Johnson wasn’t captured alive or killed at close range, dispelling a swirl of rumors about how he died. The report has determined that Johnson, 25, of Miami Gardens, Florida, was killed by enemy rifle and machine gun fire from members of an Islamic State offshoot, according to U.S.