U.S. marshals come under the Federal Authority as opposed to the State Dept. They are Federal employees. This means that the Federal government is in charge of the U.S. marshals. They send these U.S. marshals to certain cities in order to make sure that people are obeying the Federal laws. If the people are not obeying the Federal laws then it is up to the U.S. marshals to do something about it.
State department’s include those law enforcement that are hired by the individual states. U.S. marshals and State Dept officials may come together in order to solve a crime. Even back in the olden days, U.S. marshalls were still considered to fall under the umbrella of the federal government.