All federal prosecutors are part of the United States Department of Justice[1].

Here is the law and reasons: https://www.justice.gov/usam/usam-9-27000-principles-federal...

Here are the statistics https://www.bjs.gov/index.cfm?ty=tp&tid=63

1) https://www.oas.org/juridico/mla/en/usa/en_usa-int-desc-guid...