Even if they had been ghosts, this is a show about zombies. I'm pretty sure ghosts could be roaming around somewhere (probably everywhere) too with how many people have died.
Not true. Zombies have been explained away with a scientific impetus via a virus/disease/etc. So ghosts should not come into play. Well not the supernatural/mystic versions.
Edited at 2012-11-19 03:19 am (UTC)