You...are referring to the voodoo zombie, which is an act of neurotoxins. That wouldn't have any effect on the soul because they are NOT dead. They are also not really zombies in the sense of fantasy (necromancer servants, say) or modern (viral-made ones or George Romero zombies).
I'm basically speaking of all the actual zombies. Whether you mean Romero, Resident Evil, or World War Z, the notion here is that the human has expired beyond recovery, not been suspended. Mind control is mind control and zombie-ism is zombie-ism. And never between shall they meet.
Romero zombies, by the by, some to have some sort of past-life-memory of when they were alive. However...these are flashes of info, not personality. Not even in Romero's world where a zombies HAS figured out how to use a gun have they ever retained any humanity or memory or mercy that would make them human. Ergo, the soul has fled and will not be back.