Plenty of people have been tried on federal charges for murder. There was a case here in Utah in the early 80's where a man was tried and convicted of depriving two black men of their civil rights by killing them - Joseph Paul Franklin was the killer, he "sniped" the two guys because they were jogging in the park with two white women. Since the feds didn't have the death penalty at the time, I believe he is still rotting in prison somewhere. The SLC black community was understandably in an uproar, and insisted that the FBI get involved in the investigation, which they did. So they had to bring federal charges against the guy. If the Utah police had been able to solve the crime (always a question mark) and he had been charged locally, he might be on death row now. Or maybe not.