I wasn't involved but I do recall the accident, mainly because I might, in very slightly different circumstances, have been the pilot but I won't elaborate why.
On Pumas, both doors were/ are opened on short finals so the crewman can give his talkdown. The Major was possibly snoozing in the aircraft and had then been awakened by the cold air coming in after the first door was opened. The crewman moved across to the second door and subsequently heard a shout. As he turned, there was an empty seat..... Tragic.