Anyone with a cursory knowledge of police & poling will know there are policies & procedures for everything, and not following them may leave your arse hanging out to dry, no matter how barmy or wasteful the policy is.
When the Met discovered the headless body of a male in a river in Wimbledon last year, they found the body to be badly decomposed, full of maggots & missing a head.
Police officers are experts in several things, the criminal law & drunkeness for instance, but they are not experts in medical matters. They therefore are unable to say that a decomposed headless person is dead.
So despite the bleeding obvious, the Met called in a Ă‚Â doctor to attend the scene so the doctor could say that life was extinct. God forbid they get it wrong & they take a live headless body to the mortuary, just think if the civil litigation costs if they got it wrong.