Deactivated Facebook friends can spy on you: report
Forgotten Facebook friends who don't appear in your friends list — and who you can't unfriend — could still be snooping on you from time to time, new research shows.
21 Mar 2012 ... Forgotten Facebook friends who don't appear in your friends list — and who you ... It enables a person to deactivate his own account and then later, upon ... Once the crawling has finished, the attacker will deactivate again.".