Fox News has obtained shocking exclusive videos of cattle mutilation scenes from the San Luis valley in southern Colorado.

"It’s the greatest unsolved crime spree in history," says author Chris O’Brien, who recorded the videos. He wrote about his findings in his book, Stalking the Herd: Unraveling the Cattle Mutilation Mystery. 

The videos depict the grizzly nature of more than a dozen cattle mutilations. Mutilations differ from typical livestock deaths because the carcasses are found with body parts removed in an unusual fashion.

The never-seen-before footage is featured in the latest episode of Tucker Carlson Originals, which is available now on Fox Nation.

BEARDED BUTCHER ATTRIBUTES CATTLE MUTILATION TO 'EXTRATERRESTRIAL ACTIVITY'

The San Luis cases are just a handful of more than 10,000 mutilations that have stumped ranchers and investigators across the United States for decades. 

Just this month, ranchers in Delta Junction, Alaska reportedly found the remains of a cow that was missing its udder, eyes, and reproductive organs.

In 2019, cowboys at the Silvies Valley Ranch in eastern Oregon found five bulls mutilated in a remote stretch of forest.

"There was no forensic evidence of any kind left at the scene," according to Colby Marshall, vice president of the ranch at the time of the mutilations. Marshall says the bulls were missing their blood and reproductive organs when they were found.

"Each one of those bulls would have produced 20 calves a year for probably the next 5 or 6 years. Their overall production value was in the hundreds of thousands of dollars," he said. 

The ranch offered a $25,000 reward for information that would lead to an arrest. They got no credible leads.

"I would have never thought this would be possible, that you could basically kill five bulls without any evidence," Marshall says. 

OREGON COW MUTILATIONS SPARK CONSPIRACY THEORIES: 'A LOT OF PEOPLE LEAN TOWARD THE ALIENS'

At least eight other cattle were reported mutilated in Oregon since the Silvies Valley Ranch cases. No culprit has been identified.

"The ones I’ve been involved in, we haven’t solved any of them," says Sergeant Tom Roark of the Lake County, Oregon Sheriff’s Department. "There was no evidence, no clues of a suspect." 

Ranchers have reported mutilations for centuries, but the cases peaked in the United States in the 1970s.

"Investigators kind of agree there were upwards of a thousand cases just in Colorado alone," O’Brien says.

As the episode explores, In 1975, The Denver Post reported that the U.S. Bureau of Land Management canceled aerial land surveys in the area because officials "are simply afraid their helicopters might be shot down by ranchers and others frightened by cattle deaths." 

On three separate occasions, sitting United States senators including Harrison Schmidt (R-NM), an astronaut who walked on the moon, called on the FBI to investigate the mutilations.

"Either we’ve got a UFO situation or we’ve got a massive, massive conspiracy which is enormously well funded," he told a local paper at the time.

ABDUCTIONS, UFOS AND CONSPIRACIES: NEW FOX NATION SERIES EXAMINES PEOPLE, PLACES CONNECTED TO ALIENS

Declassified FBI documents show that in one investigation, the bureau referred the case to the U.S. Fish and Wildlife service, which blamed "small mammals such as foxes and opossums," but didn’t explain how predators or scavengers were able to make precise incisions.

In other instances, they claimed they didn't have jurisdiction in the matter. 

Other investigators drew different conclusions. A New Mexico state trooper named Gabe Valdez who conducted multiple investigations concluded that "these mutilations are the work of the U.S. government."

Others have suggested that the mutilations have been caused by cults, ranchers, and even UFOs.

"I can poke holes in any theory that’s trying to explain the cattle mutilation mystery," says O’Brien. "It’s really difficult soundbite material."

CLICK HERE TO JOIN FOX NATION

Subscribers can now stream Tucker Carlson Originals: Cattle Mutilations on Fox Nation.

Charles Couger is executive producer of Tucker Carlson Originals. Kyle Rothenberg and Thomas Read contributed to this report. 

Fox Nation programs are viewable on-demand and from your mobile device app, but only for Fox Nation subscribers. Go to Fox Nation to start a free trial and watch the extensive library from your favorite Fox News personalities!