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A retired U.S. Army sergeant is recalling his face-to-face encounter with alleged nine-foot-tall creatures during a military exercise, warning that the massive beings are lurking in the American heartland as new sightings emerge in Ohio.

Todd Neiss, a longtime skeptic who used to dismiss Bigfoot as an urban legend, is now the head of the American Primate Conservancy. He joined "Fox & Friends First" to discuss the encounter that shattered his skepticism and changed the course of his life.

"All that changed for me in 1993 while conducting a military exercise in the Oregon Coast Range," Neiss said Tuesday. "Those 25 seconds changed the entire course of my life."

He explained that he and three other soldiers were conducting an exercise involving high explosives when they came upon three of the alleged creatures, which he said were observing their movements.

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Split image shows alleged Bigfoot photo and researcher Todd Neiss.

A split image shows, left, a photograph said to depict the American version of the Abominable Snowman, reportedly taken near Eureka, California, and, right, Bigfoot researcher Todd Neiss, a former skeptic who now leads the American Primate Conservancy. (Bettmann/Getty Images; Screenshot/"Fox & Friends First")

"Their silhouette was completely disproportionate in terms of the arm length and even the length of the legs as it pertains to a human torso," Neiss said.

"The ones I saw range between seven to nine feet in height. They do tend to have a more human-like face, but obviously just hair-covered, very large, very athletic," he added.

While many associate the creature with the Pacific Northwest, Neiss said Ohio is a major area for reported activity and ranks fourth in the nation for sightings. 

Earlier this year, investigators with the Ohio Squatch Project investigated eight sightings reported in March, with assistance from the Bigfoot Society.

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On Sunday, FOX 8 reported that witnesses found what they described as "new evidence," including tracks and audio of unexplained howls.

Mike Miller, co-founder of the Ohio Night Stalkers Bigfoot Research Group, said a difficult winter may have pushed the alleged creatures into more populated areas, or that they were rearing their young.

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A Sasquatch Bigfoot standing in an autumn forest.

There's new evidence out of Ohio reportedly linked to the recent sightings in the Northeast part of the state. (Getty)

Neiss' investigations have taken him on long-term expeditions in Northern California, Arizona, Alaska and the Cascade and Blue Mountain ranges.

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When asked why technology hasn’t confirmed the species, Neiss said it comes down to simple math and luck. He said even with large numbers of cameras, capturing evidence would be difficult due to the species’ rarity.

"They're just a very rare species," Neiss said. "It’s just the odds of getting one to fall just right through that particular picture zone. It's very, very difficult."