The Doomslayer (The Source KE contract)

Does anyone know how on earth I’m meant to take out Lion Forest (the golfer out of bounds) - I’ve tried sniping him and it isn’t working. The ‘in the distance’ challenge doesn’t seem to work either. Any idea? I’ve got everyone else on the map - just this one guy left.

Go close to the basement entrance, if you scope with your sniper without instinct you can see his arm. Shoot that and he will die. You can even kill him with SMG, Shotgun, whatever you want.