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Liberation Front. Part of it reads, "We will now be doubling the size of every device we make."

"I'll ask you. Why does someone build an improvised explosive device with shrapnel, nails and such, if they're not intending to cause someone grievous harm if not worse?" says Lewis.

There is a definite split in the movement when it comes to violence.

After torching a forest research station in Irvine, Pennsylvania, one ELF cell threatened to "pick up the gun."

"I think it's sort off disingenuous to say 'Well, we can burn down buildings. But we can't use explosives. Or we can use explosives. But we can't do anything that might harm a person.' I think what we have to do is look at the big picture. We have to look at what works," says Dr. Jerry Vlasak.

Since our report first aired last fall, the FBI announced the arrests of 11 people, saying they were part of a criminal group that called themselves "The Family." They're accused of committing over a dozen arsons and other acts of sabotage nationwide, including those fires on top of Vail Mountain.

By Graham Messick

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