Sgt. Wolf was a soldier who was outfitted in the US BLACK OPS. He lost sight in one of his eyes after a failed rescue mission. He got pinned by an unknown assailant and was stabbed in the eye with a knife. After tossing the attacker down on the floor, he promptly beat the man to death with his bare fists. After being sent to Chernerus to investigate a possible patient zero, his team was completely wiped out leaving him as the only survivor. He vowed on that day to kill as many as these dead freaks as he could before he died. If he came across any survivors, which didnt seem likely, he would help them survive as long as possible.