The shark disappeared and then its tracking device washed up on a beach four months later.
According to data on the device, the shark's temperature rose rapidly and then quickly plunged, indicating that the shark may have ended up in another animal's digestive system.
Based on that assumption, it has been theorized that the shark was eaten by a "colossal cannibal great white shark."
The mystery is documented in the Smithsonian Institute's Hunt for the Super Predator, which is based on the Australian documentary The Search for the Ocean's Super Predator and will air June 25.
"When I was first told about the data that came back from the tag that was on the shark, I was absolutely blown away," filmmaker Dave Riggs reportedly says in the documentary.
"The question that not only came to my mind but everyone's mind who was involved was, 'what did that?' It was obviously eaten. What's gonna eat a shark that big? What could kill a [9-foot] great white?"