Mueller decided the case(s) were not in his scope. Mueller referred the cases to USA in SDNY. USA in SDNY requested and obtained warrant from federal court in SDNY. FBI, under USA/SDNY executed the search warrants.
I was focusing on the fact that a judge granted this crap warrant, amazing in itself.
But, you raise an interesting point. If Mueller decides these aren’t in his scope, whose scope are they in? Is there a prosecuting attorney from SDNY? Or is the FBI just doing its Deep State investigating? Will Mueller get to poke through Cohen’s stuff? Or are the people of SDNY doing it?