"Maybe that was true in the past, but today when you delete your data it is gone. Trust me, I wrote it myself. The law enforcement guidelines that have been circulating recently corroborate this."[0]
"If you don't think you'll use Facebook again, you can request to have your account permanently deleted. Please keep in mind that you won't be able to reactivate your account or retrieve anything you've added. Before you do this, you may want to download a copy of your info from Facebook. Then, if you'd like your account permanently deleted with no option for recovery, log into your account and let us know."[1]
[0] https://news.ycombinator.com/item?id=3320240