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.
Tutankhamun
There was strong suspicion in 2015 that in the north wall of Tutankhamun's tomb chamber was a doorway, blocked and hidden by decorated plaster, leading to another chamber, which was purported to possibly contain a burial of Nefertiti.