Doubt it wasn’t killed by humans. In photo 4 it looks like its head isn’t even attached. Could be wrong though.
This breaks my heart! I was extremely fortunate to swim mere inches from two of these AMAZING and gentle creatures when we did SharkCam 2011. They were so gentle, but you did have to be on the lookout of that 7’ tail. She could accidentally whap you with it as she swam by. A sad day indeed.