Dead Rising 2
Sergeant Dwight Boykin leads his squad of soldiers into the infected city to begin the rescue operation. He kills the first zombie for his squad, and then commands them to separate and clean up the area in Fortune Park, beginning the operation. Everything goes smoothly, up until an unfortunate soldier is overtaken by the new, and surprisingly quick and powerful gas zombies. His squad is quickly killed and consumed in front of him, only partially concealed due to the new green fog of gas. He flees from the advancing zombies in his nearby Humvee and escapes into the underground tunnels. He appears to begin suffering an extreme case of dissociation immediately after his initial escape, believing his deceased comrades are still alive, interacting with their bodies even though they are obviously no longer living.
When Rebecca Chang follows him down into the tunnels to investigate, he takes her hostage for unknown reasons; (possibly seeing her as a survivor in need). He is fending off invading zombies, while commanding his dead soldiers 8-Ball, Curtis, and Jonesy to cover flanks and provide ammo and weapons. Beyond Rebecca, Dwight seems to immediately see Chuck as a zombie, perhaps speculating that Rebecca found him before his mental state deteriorated further, and forcing Chuck to fight him.
After he is defeated, he uses a grenade to commit suicide, to prevent Chuck from biting him.