Missing details about Don's dive problems

This is a fascinating documentary but skips over some important details, for instance it wasn't made clear why Don Shirley went past his expected maximum depth - I suspect he expected to meet Dave on the way up and just continued down but at no point was this explained, but this doesn't seem like a mistake an experienced diver should make. He then had issues on the way back up, yes his dive computer broke, but did he then rise too fast and get the bends? Again it wasn't made clear if this was the reason for his physical issues, so I'm just guessing, perhaps he's trying to protect his reputation. However Don's issues had no bearing on Dave's tragic situation.