in our congregation in western ky , (early 90s) a man who was being studied with was a child molester who had abused his own daughter.he attended the hall for a good 2 yrs or so. it wasnt known by anyone but the elders and THEIR kids. thank goodness one of my children was a good friend of one elders daughter who told her but told her not to tell anyone. she told me and i sat and had a talk with all my kids to avoid this man. he eventually quit coming to the hall but i remember being outraged that the elders made sure THEIR kids knew but not anyone else. and i have 4 kids. i also mentioned to other mothers in the hall who had kids what i'd learned and none of them knew.
its not a problem exclusive to the jw religion but like someone said above.. jw's are the only ones who send people door to door. and who keep things quiet to the rank and file. only the kids of elders are "protected" by knowlege of who may be a danger.