When you are chained to a wall, and become weaker over time, you sink down to your knees if they can reach the floor, or maybe even if they can't reach the floor. Subsequently, I wouldn't place too much emphasis on the whole "kneeling position" thing. More emphasis should be placed on how they were attached to the wall. Was it chains and shackles that required "keys", or was it rawhide strips or rope? One would suggest Spanish, the other Apache, in my humble opinion. And we don't know if they were put to the blade or not, more likely they were simply never released from their bonds, and died from lack of water and food. Unless we have a skeleton to examine forensically, or perhaps photos of the site before it was destroyed, guessing is all we can do.