This is one of the few things that I think should be federalized. Child molesters commit their crimes in one state, get a slap on the wrist, and then move to another state to commit more crimes. Congress should make child molestation a federal crime, with a high sentence.
Another advantage of doing that is that it would absolutely drive the libs nuts that the conservatives were using their own invention--federal preemption--to increase criminal penalties on what were previously state crimes. It might even prompt the Dems to make an about face and embrace federalism. For example, I can envision the Vermont lawmakers complaining that the US government was interfering with their internal affairs. It would be delightful to be able to respond the way they have for the last 70 years every time the feds took over what was previously a state function: "Tough."
Murder isn't even a federal crime, nor should it be.