Video shows him aiming the pistol at the fleeing Kyle, not up into the air.
Since redshirt was shot in the back, ballistics may show if the pistol shots killed him. The dude firing the pistol tossed it away when he went to render aid to red shirt. Another witness said a girl asked him twice if HE shot the guy.
How likely is it that an AR-15 could fire a round into his back leaving no front exit wound? He was shirtless on the video and there wasn’t any blood.