It wasn't that long ago that it was widely accepted amongst scholars that Tutankhamun may have been murdered by some kind of physical attack. Bob Brier put vast amounts of thought, theory, and hard work into showing the world those possibilities; he was the biggest believer in this theory. However, more recent scans have shown that the bone loose in the skull was produced during mummification (when the brain was extracted from the nose), and one serious candidate for his cause of death is his injured knee. It's still certainly possible that there was foulplay when Tutankamun died (poisioning is possible, as well as the knee injury may not have been entirely accidental), but the injury to the head didn't even happen, so it's not even a possibility. Bob Brier later admitted that his murder theory was wrong. To be able to admit that you were incorrect about something is an admireable quality in a person, as it shows a great passion for learning (at least, I
think it does). No-one can say for sure whether Tutankhamun was murdered or not, but they can say with some confidence that it had nothing to do with the head injury.