I know all about them. And they do not have primary jurisdiction over any death case that isn’t on federal property. And even that is very rare.
Some things they are good at and in many ways are the best of the feds. But they really aren’t very good at basic street cop and Sheriff work. I know we all loved Tommy Lee Jones in the movie. But calling the Marshals for a death is like calling a federal agency to investigate your car wreck.
The fact is, 99% of what they do is security details for judges and inside Federal courthouses, transporting prisoners, and much more are, looking for fugitives. At a murder scene they aren’t much use.
Primary jurisdiction is always with the sheriff.
This “above your head and you better call the feds, but im not going to even tell you why” is a peek into the mentality of guys like poindexter, his buddies on the court, his getting awards from Obama, etc.
By they way, the marshals are the security detail. If the protectee is laying there dead, can you think of why that is the last people you would have investigate that death? It’s pretty obvious that the security unit doesn’t get to investigate why the protectee died.