Tutankhamun's mummy
Detective Michael R. King and FBI profiler Gregory M. Cooper came together with an actual Egyptologist to form their own theory which was that Tutankhamun was murdered. With the use of forensic evidence and their extensive backgrounds in criminology, they came to the conclusion that he was likely murdered by one of his closest advisors, Ay. Ay did succeed Tutankhamun on the throne, so they used that as the motivation for the murder.
Nefertiti
It is possible Nefertiti is the ruler named Neferneferuaten. Some theories believe that Nefertiti was still alive and held influence on the younger royals. If this is the case, that influence and presumably Nefertiti's own life would have ended by year 3 of Tutankhaten's reign (1331 BC). In that year, Tutankhaten changed his name to Tutankhamun. This is evidence of his return to the official worship of Amun, and abandonment of Amarna to return the capital to Thebes.