SOP when someone goes missing on a ship (as opposed to seen going over the side) is a 'thimblehunt'. For exercise, the subject usually gets himself well and truely hidden and the exercise drags on. In reality, a search sticks to the places the subject would likely go in the course of his duties or other lawful occasions. Not found, assume he's overboard.
From the BBC link in post one,
He was discovered in a store room with a broken leg and back injuries.