To fit the pressures we've faced throughout the years and our internal obligation to be international police.
Article III, Section II, US Constitution:
The trial of all wrongdoings, aside from in instances of impeachment, will be by jury; and such preliminary will be held in the state where the said wrongdoings will have been submitted; yet when not conferred inside any express, the preliminary will be at such place or places as the Congress may by law have directed
The first answer is correct.
Serious crimes are conducted in the state court system unless the charges involve multiple states, non-citizen immigrants, or a foreign ambassador.
