A spate of mutations in the 1970s caught the attention of the FBI, however, they were unable to investigate because of a lack of jurisdiction. Dee Browning/Shutterstock

Something strange is going on in eastern Oregon. Over the past four decades, ranchers have been finding a slow but steady stream of their cattle dead with neatly severed genitals and other clear signs of mutilation.

After a brief hiatus, it now looks like the problem is back. The Oregon Cattlemen’s Association released a statement on August 5 announcing that five bulls had recently been found dead at Silvies Valley Ranch in Oregon. The bulls had “several organs” removed, although there was no sign they had been shot, poisoned, or attacked by a predator.

More specifically, the Associated Press reported this week that their bodies were all completely drained of blood, and their sex organs and tongues were removed.

Over the past couple of decades, cattle across the eastern stretches of the state have been found dead in equally unusual circumstances. According to Oregon Public Broadcasting, a cow was killed on a remote ranch in the 1980s, while other cattle have been found dead near Princeton and Burns over the past couple of years.

A report from 1975 in The New York Times states that almost 200 cows had been killed in 11 different western and mid-western states. Interestingly, even four decades ago, police believed the crimes were linked to an “Oregon group said to be enlisting followers for a trip to outer space.” This spate of mutations in the 1970s even caught the attention of the FBI, however, they were unable to investigate due to a lack of jurisdiction

The Harney County Sheriff's Office is currently working on the premise that this was carried out by a cult, perhaps as some kind of ritual sacrifice. However, unsurprisingly, the rumor mills are stirring in rural Oregon, with local residents gathering all kinds of wild theories, ranging from Satanists and bigfoot to a North Vietnamese army and – of course – aliens.

“A lot of people lean toward the aliens,” Harney County Sheriff's Office Deputy Dan Jenkins told Oregon Public Broadcasting. “One caller had told us to look for basically a depression under the carcass. Because he said that the alien ships will kinda beam the cow up and do whatever they are going to do with it. Then they just drop them from a great height.

“Another told us we should run like a Geiger counter type thing around the animal and guarantees that there would be radiation there,” Jenkins added. “And the number one on the list there, he thinks it’s the North Vietnamese army.”

The Oregon Cattlemen’s Association has said it will pay a cash reward of up to $1,000 for information or evidence resulting in the arrest or conviction of those involved. The Silvies Valley Ranch has also announced an award of $25,000 for information leading to arrest and conviction.

Meanwhile, the mystery continues.