Mark was found wandering around the Entrance Plaza, trying to convince himself that he was not afraid of the zombies. When the zombies broke into the plaza, he attempted to flee, but was killed before he could reach safety.
Regardless of Mark saying "They won't get me". He doesn't fight back at all, and dies like a coward.
Despite the fact he won't fight back, he sometimes survives for quite a while, usually because the zombies turn their attention towards Frank or other nearby survivors.
Mark is one of the few survivors who doesn't appear in Infinity Mode.