Researchers say they're about to revisit a mystery of the ocean that has had them puzzled -- what kind of enigmatic sea creature could have devoured an almost 10-foot-long great white shark in waters off Australia?

As part of the country's first extensive shark tracking program, a tracking device was attached to the female shark dubbed Shark Alpha 11 years ago to track her movements along the coastline of Australia.

Then the shark disappeared, and the tracking instrument washed ashore 4 months later where it was found and picked up by a passerby.

In a new Smithsonian Channel documentary, "Hunt for the Super Predator," researchers explain why they think the big shark was eaten -- by something even bigger.

Data recovered from the tracking device showed the shark suddenly plunged more than 1,900 feet down the continental shelf. And although the ocean water gets colder the deeper you go, that tag got hotter, from an initial 46 degrees F to a high of 78 degrees.

The only conclusion, they say, was that the tag -- and the shark -- must have been completely inside another animal.

"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 says in the upcoming 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 going to eat a shark that big? What could kill a 3-meter great white?"

There has been no shortage of theories offered as to what could have consumed the shark, from killer whales to giant squid, but most scientists say they believe the predator was likely another, but much bigger, shark.

The attack may have been the result of a territorial disputed or possibly extreme hunger on the part of the larger animal, they say.

The thought of a "colossal cannibal great white shark" is not so farfetched, they say; such shark cannibalism has been seen before.

Off Australia's Queensland coast in 2009, a 20-foot shark was observed taking a bite out of a smaller great white.

"That cannibal thing is what great whites do," Australian shark expert Hugh Edwards said. "They'll eat anything, including their own kind."

The Smithsonian Channel will air "Hunt for the Super Predator," inspired by a previous Australian documentary examining the mystery, at 8 p.m. June 25.