The first wild alligator snapping turtle found in Illinois in 30 years might have wandered a creek's depths "like a zombie," the last of its kind in the region.

That's according to University of Illinois researchers who reported recently in the Southeastern Naturalist journal on a rare find that could spell hope for the state's endangered species — or hint at its decline.

Reptile biologist Chris Phillips of the Illinois Natural History Survey dove into the waters of Clear Creek, located near the state's southern tip, in 2014.

He hoped to find a male alligator snapping turtle with a transmitter on its back, one previously released in the area with hopes of spurring population growth.

His hand eventually felt a shell, but one way bigger than expected: It belonged to a 22-pound female alligator snapping turtle measuring 15 inches long, twice that of the intended male, the university's news services reported.

Illinois graduate student Ethan Kessler holds the turtle.

DNA tests revealed the turtle, at least 18 years of age, was native to a region that makes up the northernmost end of the species' range. 

The big question, then: Are there more wild alligator snapping turtles undiscovered in the area?

If so, researchers could help bolster that population of a species listed as endangered in Illinois since 1999.

Dredged rivers, drained swamps and new dams all addd to the turtle's widespread decline over the past century, the report says. 

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But Illinois grad student Ethan Kessler, a co-author of the study, says the female could long be the last wild alligator snapping turtle in the state.

“When a population dies out, a single turtle may wander around like a zombie waiting for the end of its days," he said.

Such turtles live up to 100 years. Researchers, if they live long enough, won't likely observe the turtle's life: Her new transmitter's battery died after she re-entered the wild, and finding her the in waters' depths again make take another 30 years.

Follow Josh Hafner on Twitter: @joshhafner