Yes, the US Marshall Service is part of the Department of Justice.
https://en.wikipedia.org/wiki/United_States_Marshals_Service
And, although they operate under the direction of the Attorney General, the following brings up an interesting point:
The Marshals Service serves as the enforcement and security arm of the U.S. federal judiciary
If the court issues an order and the attorney general subsequently refuses to enforce that order, couldn’t the court then issue an order placing the attorney general under arrest?
Fyi the us marshals are the enforcement arm of the Federal judiciary. There is one marshall and one cheif deputy marshall per us district court.
The marshals are the group that would most likely do the arrest in this hypothetical situation. For example the FBI is mostly investigation and usually when they get enough information for an arrest they pass it off to the marshals if it’s a federal crime.
My contention is that the DOJ (who oversees the marshals) would order them to ignore the bench warrant.
Courts have the power to deputize whomever they choose. If they were to deputize, for instance, a state police officer because the marshalls wouldn’t carry out their orders, my belief is that no deputized agent would arrest someone for contempt if some LEO under federal control (FBI, the marshalls, capitol police, etc.) was protecting the person held in contempt. You will not get two sets of cops shooting at each other over this.