They act at night. Their weapon of choice is fire. Their targets include university offices, timber companies, ski resorts, luxury homes, wild-horse corrals, fur farms and egg-farm warehouses. Their intent is to defend the environment, animals or human health.
This radical movement is composed of what authorities believe are small, secret and tightly organized cells of individuals. Though the Pacific Northwest is the epicenter, activists have blazed a cross-country path from Washington to Long Island, N.Y.
The crimes have increasingly preoccupied the FBI, which now lists two of the most high-profile groups - the Earth Liberation Front and the Animal Liberation Front - as domestic terrorists. But so far, the FBI has been unable to solve most of the major arsons.
The investigative list grew longer Monday as the University of Washington's Center for Urban Horticulture suffered as much as $3 million in fire damage. Officials say the fire was started with the same sort of incendiary device used in a fire simultaneously at a poplar-tree farm in northwest Oregon. No one has claimed responsibility for the fires.
"The arsons have been increasing in intensity, and there is also a shrinking of the calendar dates between each event," said Phil Donegan, the FBI's acting special agent in charge in Portland.
"We're definitely devoting more resources to this."
Spokesmen for the two high-profile groups say the arsons are carefully planned to avoid risk to human life. But FBI officials and others tracking the crimes say not all the arsons are claimed by the two groups, and that some of the incidents have posed significant risks to firefighters and others.
"I think it's only a matter of time before someone gets hurt," said Capt. Thad Buchanan, a police-department investigator in Eugene, which has seen more than 120 suspicious Dumpster and structural fires during the past 14 months.
In Washington state, the FBI is investigating more than a half-dozen arson and vandalism cases during the past four years for possible links to the radical movement.
The list is much longer in Oregon, with the biggest concentration in Eugene. In that town, arsonists have hit a wide range of targets, including a business brokerage office, a golf course, a police substation, an organic-food store and a Chevrolet dealership where more than 20 SUVs were torched in March.
Oregon also is home to the most prominent public face of the movement - a vegan baker named Craig Rosebraugh who runs the North American Earth Liberation Front Press office out of Portland.
Rosebraugh is a thin, serious 29-year-old who operates what he describes as a "a legal, above-ground news service dedicated to exposing the political and social motives behind the covert direct actions of the underground Earth Liberation Front."
Whenever that group - known as the ELF - takes responsibility for an arson or other action, Rosebraugh said, he researches and verifies the claim before giving the communiqué to the media.
He said arsons are done by small groups - from three to 10 people - that are not only kept a secret from him and the public, but from each other.
Rosebraugh has been subpoenaed to testify by a Portland federal grand jury. And earlier this year, the FBI made a second raid on his office to seize computer equipment. But he says he has no active involvement - or foreknowledge - in any arsons.
He also has no qualms about the use of fire as a protest tactic.
"If you have someone who may be destroying the planet, it's only sensible to go in and burn the place down and cause as much damage as possible to that economic entity," said Rosebraugh.
Mainstream environmental groups denounce such tactics. Speaking yesterday at The Evergreen State College in Olympia, Rosebraugh said such groups are not the answer.
"The popular environmental movement has failed and failed miserably," he said. He questioned whether the mainstream environmentalists are part of a movement at all because "to be a movement you have to move somewhere. You have to progress, right?"
Rosebraugh said early ELF actions struck largely against logging activities deforesting the landscape, and then spread to arsons such as a $12 million 1998 fire aimed at an expansion of Vail Mountain ski resort in Colorado.
But arson has been embraced by a broader group of activists, including the Animal Liberation Front, which jointly claimed responsibility with the ELF for a 1998 fire that wiped out $1.5 million worth of research and caused $400,000 in structural damage at U.S. Department of Agriculture research stations in Thurston County.
Radical critics of bioengineering also have been involved in widespread illegal actions.
In the past decade, researchers have been able to splice the genes of one organism into another, creating - for example - a poplar tree with special resistance to disease or a potato with resistance to bug infestations. This technology has potential to increase crop yields and vitamin content, as well as reducing pesticide use.
But splicing genes is controversial, with some scientists and environmentalists contending the technology poses risks to wild plants, insects and human health.
A news release distributed earlier this year by a Tennessee-based group called GenetiX Alert claimed that more than 40 "anti-genetic" actions had been carried out since November 1998.
Poplar farming - a relatively new style of forestry that cultivates thousands of acres of fast-growing trees - has been a focal point for activists. In March, vandals attacked poplar-research plots cultivated by Oregon State University researcher Steve Strauss. Poplar research is conducted at the UW horticulture center and the Oregon tree farm set ablaze Monday.
So far, none of the arsons has caused serious injury. But there have been a couple of close calls.
On May 27 last year, Eugene police discovered that arsonists had used an incense stick, sponge and milk jug to try to ignite a fuel-tank truck at Tyree Oil. The attempt failed. The tanker was empty at the time - but contained explosive fumes - and police say a blast could have damaged two city blocks.
None of the major activist groups - including ELF - ever claimed involvement with the attempted arson at Tyree. Two suspects with ties to Eugene's anarchist movement - Jeffery Michael Luers and Craig Andrew Marshall - were arrested in June. They were charged with trying to set fire to the tanker and setting fire June 16 to three pickups at Romania Chevrolet.
Marshall later pleaded guilty to conspiracy to commit arson at the car dealership, and is serving five years and six months in prison. Luers' trial is set for May 30.
The Romania Chevrolet dealership was hit again by arsonists March 30, with no arrests yet. The fires - lit by incendiary devices - began about 2:40 a.m.
"I peered out my window and saw flames everywhere," said Tuesday Lush, a University of Oregon student who lives across the street from the car lot. "The SUVs were exploding one after another and moving toward my house. So I grabbed my 6-year-old son and ran out into the street.''
No group has taken responsibility for the Romania Chevrolet fire-bombing. But Lush, troubled by her experience, decided to send an e-mail to the ELF Web site.
She said she has supported many actions by the group but is "struggling to understand and come to terms with the firebombings that are taking place in midst of residential communities."
Lush said she got no reply.