I also don't depend on made for TV melodramas on the Lifetime channel for verifiable facts and evidence of criminal behaviour..
As to the federal statutes here is what I know:
The FBI is involved because of federal racketeering statutes (the same thing used in many organized crime prosecutions) not because he is a polygamist or child abuser.
The plaintiffs are Richard Jessop Ream, Thomas Samuel Steed, Don Ronald Fischer, Dean Joseph Barlow and Richard Gilbert, all of Salt Lake City, and Walter Scott Fischer of Macon, Ga.
They charge that FLDS church president and prophet Warren Jeffs and Sam Barlow, a former Colorado City police chief and close associate of Jeffs, engaged in assault, terroristic threats, unlawful dealing of property, theft by extortion, child kidnaping, official misconduct and theft of services.
The above is just some of the official charges against Jeff's and others. So far most of the police department has been indicted... because Jeff's crossing state lines at will (Colorado City is on the AZ border and Hilldale the Utah border so they just step over the line when need be...
As an aside -- Jeffs raped and sodomized his brothers son's -- one could not live with it and committed suicide and the other son, now an adult, came forward and told what happened, he is one of the many witnesses against Jeffs.