I read that within the past few years, neighbors had called the authorities to report that this man (whom they knew to be a registered sex offender not allowed to have contact with children) had children walking around in his backyard. The neighbors spotted the kids, called and reported it, but it seems nothing was done.
WTH?!?!?!?!?!?!

You have a registered sex offender with a history of kidnapping, who is reported to have children on his property, and you don't search every inch of it and quiz every neighbor? Someone dropped the ball in the worst way. Yes, he had it somewhat hidden, but if the neighbors saw it, the police could have seen it....perhaps from the reporting neighbor's house.