Even deliberate aim at a human target from distances of even 100 yards away isn't likely to score a direct hit from an 40mm grenade launcher firing CS rounds. They're fairly accurate, but the slow muzzle velocity and the fact that the tear gas projectile is shedding weight by emitting a stream of CS gas during flight generally prevents the firer from scoring a deliberate direct hit on a human target, particularly a headshot. It's as unlikely as driving a golf ball with a 5-Wood and hitting someone 100 yards away on the first try.

Any 37mm/40mm tear gas projectile can cause lethal results if the target is hit in the head, that I don't dispute. What is almost assured here is that the soldier fired the weapon and Tristan's path crossed in front of it a moment later.

Best wishes and regards to the family of this man.