A crash scene is a crime scene. I am sure that the military cannot go near an aircraft wreckage until the police clear them to do so. That includes a crash on a military airfield. This was drummed into us on some crash scene officers course I did years ago. When the plod turn up at the gate, THEY have juristiction, however we were also told that they usually can't wait to hand it over as it is way to difficult to administer.
At a fatal crash overseas on ops that I was supervisor for, I tried to get to the aircraft to remove very sensitive comms documents. The redcaps would not let any of us near the scene for 3 days.