At first blush, the whole idea seems insane, a nightmare from the supermarket tabloids.

But suppose, just for a moment, that Boise native Linda Moulton Howe's theory about the ongoing animal mutilations is correct.Suppose Howe is right when she concludes in her new book, "An Alien Harvest" that - after a decade spent investigating the phenomenon - she found "an accumulation of human testimony that suggested the presence of extraterrestrial mutilators."

Or, as she states so forcibly in interviews: "There isn't any question in my mind that there is an alien life form that intrudes on this planet for reasons I don't yet understand."

She and other UFO investigators also believe the federal government knows of these intrusions and has aggressively covered up about it for decades.

Other researchers have documented eyewitness sightings by high government officials, including the first director of the CIA, astronauts, pilots, air traffic controllers and thousands of ordinary citizens.

Documents obtained through the Freedom of Information Act have revealed even more sightings (including one in 1987 near Emmett) and investigations the government has previously denied conducting.

"It's the best-kept secret in the world," Howe says.

If she's right, she acknowledges, the impact on this planet would be incalculable.

"But," she adds, "for people to deny it, won't make it go away."

What won't go away are the thousands of mutilations that have occurred worldwide since 1967, including a recent rash in southeastern Idaho.

Bear Lake County was hit by 15 cattle mutilations in a recent two-month period, says Sheriff Brent Bunn.

Mutilations first hit the headlines in the mid-1970s. There were 90 cases in Idaho, and one newspaper alone ran 50 stories on the subject between June and December 1975.

The pattern is disturbingly similar, no matter where it occurs. Somehow, the blood is drained completely, and there are never any footprints or tire tracks near the carcass.

The animal usually has an ear missing, one eye is carved out in a perfect circle, flesh is stripped from one side of the jaw, the tongue is taken from deep in the throat cavity and long strips of stomach are removed, as are the sex organs.

To duplicate the cuts with current laser technology, Howe discovered, would require equipment weighing 500 pounds and take up to two hours.

In the 1970s, public investigations, including one by then-Attorney General Wayne Kidwell, were launched and rewards were offered in several states.

Satanic cults and UFOs were on the list of suspects, but the conclusions reached by investigators in Idaho and Colorado was death by natural causes and mutilation by predators.

An ex-FBI agent named Kenneth Rommel was hired by the federal government and in 1980 wrote a 300-page report. He concluded that, without exception, the deaths and wounds were of natural origin.

Howe angrily dismisses Rommel's report as an "obvious paid-for whitewash that didn't even deal with the real cases."

"I don't know of a predator that would (cut up an animal that way) with so much soft tissue available," Sheriff Bunn said. "It doesn't make sense to me. But then it doesn't make much sense that people would do this and leave all the meat."

Lou Girodo, now sheriff of Las Animas County in Trinidad, Colo., has investigated 100 mutilations over the past 13 years. He says, "I grew up on a farm, and I know what a predator does. They grab, tear and gnaw."

Girodo says he has seen coyotes circle a mutilated cow repeatedly, but they wouldn't come in for a free meal.

"I've never seen coyotes act like that," he says. "Like everyone else, I'm trying to come up with an answer."

That was the debate Howe found when she began to investigate the story in 1979.

"I was a journalist and filmmaker (for KMGH-TV in Denver) who was provoked by the mystery of these bloodless animals," she said from her Atlanta office.

"I knew I was getting into something that was unexplained but thought I could get into it and come up with the definitive answer. It was like walking into quicksand."

The turning point came six months into the investigation when she filmed a woman named Judy Doraty, who was put under hypnosis to help her recall an incident that occurred in Texas in 1973.

Obviously terrified, Doraty relates on film how she was abducted by the aliens and witnessed a mutilation.

"That really got me," Howe says. "I said, `My God? It must be true.' "

"A Strange Harvest" won Howe an Emmy in 1980, but she continued to collect material on the mutilations and other UFO phenomena.

Eventually, she combined old and new information into "An Alien Harvest," which she published privately last year.

It cost her $45,000 to print 1,250 books, but she chose that route so she could control the content.

"It was the biggest gamble of my life," she says. "I guess it's a testimony of how much I care about how the material would be presented."

The material she gathered came from scores of interviews with eyewitnesses and government officials who told her amazing stories, despite their fear of ridicule and retribution.

In 1983, Howe was invited to Kirtland Air Force Base in Albuquerque, N.M., by an Air Force investigator. Inside a secure room, she was shown but not allowed to duplicate a document titled "Briefing Paper for the President of the United States of America."

The paper, she says, detailed UFO sightings that go back tens of thousands of years and claimed manipulation of DNA on earth's primates.

Recent encounters began in the 1940s, she says, and the paper listed dates of UFO crashes and details of live and dead aliens recovered by the government.

She admits it all sounds fantastic beyond belief, and she realizes her information poses many times more questions than it answers.

"Everybody would like it to be like the movie `E.T.' But the reality seems to be quite different."