Horrible. I don’t know who these people were or what they had done or not done, but they seem to have been staked out and have died in some way so horrible that their jaws were open at the time of death. Dreadful to see.
No, just gravity and the effects of rigor mortis.
Ever see the old movies of ‘A Christmas Carol’ where the ghost of Jacob Marley has a cloth tied around his head and under his jaw?
That is to prevent the jaw from dropping open and stiffening in that position................