How do I know if someone has deactivated their Facebook account?

[@jKLa]

Actually someone who has deactivated (not deleated) their Facebook account can still be active on messenger. If it's the seperate messenger app their pofile picture will still appear as normal in that case but you won't be able to go to their (deactivated) profile.

[@jKLa]

It might also say "using messenger without Facebook" in such a case though I've read that is inconsistent.