Zach, an engineer and technician for the Marine Corps, returned from Iraq before going insane. Struck by delusions of a terrorist attack, he killed his teammates and civilians in the mall, mistaking them for enemies. Establishing a stronghold in the food court, he exhibited aggression and violence, portraying himself as a heroic leader. In reality, he shot and tortured survivors who begged for their lives. With remarkable intelligence, Zach strategically set booby traps and baits in the mall.