A recent article I wrote, titled "A Predator is Always a Predator," discussed the 750,000 registered sex offenders in the U.S., the thousands more unaccounted for, the thousands more who've never been caught, and the fact that predators live amongst us.
http://www.huffingtonpost.com/robert-siciliano/10-ways-to-prevent-an-abd_b_3254723.html