DoJ, despite the name, is not part of the judiciary of the United States. It's firmly in the Executive branch. The U.S. Judiciary is quite literally only the Courts and their staff. Anyone with a badge, or arrest powers above the Average Joe is under the umbrella of the Executive.

This is part of why a hijacked Executive Branch is in it's own way a nigh irrecoverable Constitutional crisis short of a coup from inside the Executive, or a unified and oppositional Congress. There are precious few external-to-the-executive enforcers in other branches capable of actually holding a misbehaving Executive to account. If the President does it, it isn't illegal while he's in office.

In theory, one of the few that exist that I'm aware of is the Sergeant-at-Arms in the Legislature who can order detainment of those in contempt of Congress. This represents a political, not a traditional judicial detainment, but actually requires a Legislature willing to exercise it's ability to impeach among other things. Also, it may be the case they have to refer external to D.C. arrests through DoJ I think.

The judiciary, is firmly gated in it's enforcement power to the willingness of the executive to execute.