Weiner only was federal by a mildly obscure federal charge, using a electronic device to transmit an explicit image to a minor across a state line Pedophilia isn't really even a legal code, on the state or federal level. On the federal level it could be sex trafficking of a minor, or something similar like that. Child pornography can be federal too, but it gets technical. The FBI/HSI really has no jurisdiction over sex crimes, unless they involve a computer crime, or happened on a cruise ship in international waters or something, or an organized fashion like sex trafficking/pimping.