I am not good at the relationship name thing so here comes the hillbilly version:
My wife's, brother's, wife's, brother (got that?) is a detective for internet crimes in one of the eastern states(to remain anonymous).
He said the best thing you can do is file complaints in IC3 located here:
https://www.ic3.gov/default.aspx
The state and local police somehow can troll through the messages that come in through there to determine what types of things may be occurring that they don't know about and what may be of interest to them to go after. If something sticks out enough they can pick it up.