Behave with decorum. Take control of the situation, and treat him as you would were he still alive. Restore his dignity and his modesty by covering him completely with a blanket or duvet. Once the police have seen him, close his eyes and mouth, and cradle his head on a couple of pillows or cushions; you'll be amazed at how different he will look. Leave his face exposed if the family so wish. Tell them how sorry you were at being unable to do anything - and mean it.