There are laws in many of the 50 United States of America that the policies and practices of Jehovah's Witnesses violate. In my state we have laws that make it a criminal offense to fail to report child abuse and felonies (sexual assault of a child being a felony). Sex offenders are required to register with local authorities by both federal and state laws. Failure to do so is a new felony offense. Often there are laws that prohibit some sex offenders from being around children our public places intended for children.
I suggest identifying sex offenders in local congregations via government run websites Intended for that purpose. Educate the public and local authorities on the policies and practices of Jehovah's Witnesses in concealing such crimes/persons.