If I download my data from Facebook, will my old deleted messages still be there?
Facebook's TOS, though, is infamously murky when it comes to defining your right to user privacy. Not sure if your question relates to a concern about whether or not deleted messages are really "gone" or permanently burned into FB's server logs, but a lot of experts say the gist of it is that anything you post on FB automatically becomes their property. It's scary indeed, and Zuckerberg has often just come right out and said, basically, that user "privacy" is antithetical to what FB is all about -- sharing information with your network of "friends." The growing consensus is, too, not to put anything on FB that you wouldn't want to be known otherwise, because FB is like Vegas in that what happens there, stays there, although at least with Vegas it's more about keeping dirty little secrets actually secret.
Caveat confessor, I guess.
It depends when Facebook takes a snapshot of user data. If Facebook archived your data right now and you deleted some messages after they did that, you would have to wait until the next snapshot was taken before changes would appear. So if the messages were more than a week or so old, I doubt they will be there.
How Useful is Facebook's "Download Your Information" Feature in E-Discovery?