From facebook's perspective, what would the signs be? Not logging in for days/months/years probably isn't enough. Age might not help (I've told countless websites that I am 100+). Even searches tied to obituaries would yield countless false positives for deaths.
Imagine if the Facebook robot thought you were dead, then asked you to confirm. "Login to your account or we will announce your death to all of your friends."
Imagine if the Facebook robot thought you were dead, then asked you to confirm. "Login to your account or we will announce your death to all of your friends."