At the ensuing trial, Clausen showed up with a camera and a notepad. During a recess, he approached the activists in the parking lot, posing as a journalist. "I'd really like to get an interview," he told them. Not now, they said, talk to us after the trial. He pushed ("I'm a friend, come on,") and eventually one of them, he says, admitted his ties to ALF.

"That," Clausen chuckles, "is how stupid they are."

It bears noting that "ties" to extremist groups like ALF and ELF are tenuous by design. With no hierarchy, no communication between cells, and no leaders—only "spokespeople" like ELF's Craig Rosebraugh and ALF's David Barbarash—these groups maintain a membership-by-deed policy. You or I could become a "member" of ALF tonight by gluing the locks of a butcher shop and publicizing the deed on the group's Web site.

As ecotage, this is far more cold and calculating than the Merry Pranksterish ethos of Clausen's dread nemesis, Earth First!. Cofounded in 1980 by five fed-up enviros, including former Wilderness Society lobbyist and de facto ringleader Dave Foreman, Earth First! was supposed to be "a new joker in the deck," pledging militancy and what Foreman called, with a tip of the hat to the novelist Edward Abbey, "monkeywrenching"—the kind of creative sabotage employed by tea-dumping colonists and IWW unionists of yore. By being unabashedly radical—questioning the notion of "progress" and embracing direct action—Earth First! provided cover for mainstream environmental groups. Yet it also pressed bold ideas (dam removal, Deep Ecology, a logging ban in national forests) that were later championed by the environmental old guard.

Earth First!ers became the shock troops of the environmental movement by employing shocking tactics. Tree spiking, an old Wobbly trick, attracted plenty of press, most of it bad. In 1987, a 23-year-old mill worker in Cloverdale, California, was hospitalized with facial wounds when his saw blade shattered upon hitting a 60-penny nail embedded in a second-growth redwood. Earth First! was never found responsible for the incident, but it didn't make much difference; its advocacy of spiking was common knowledge. (Foreman had even published lessons in his 1985 manual, Ecodefense.) In the early 1990s, however, Foreman and other leaders left Earth First! and the group modified its tactics. Judi Bari, a leader of their Northern California Headwaters forest campaign, convinced the organization to renounce tree spiking and other forms of monkeywrenching and turn to gentler modes of civil disobedience (like Julia "Butterfly" Hill's two-year stint in a northern California redwood). "It's time to leave the night work to the elves in the woods," she wrote in the February 1994 issue of Earth First! Journal.

The elves were happy to oblige. Earth First!'s mainstreaming ushered in an alphabet soup of ecotage groups willing to take up the monkey wrench. And then some. ELF announced its arrival in October 1996 by torching a Forest Service pickup and leaving an unexploded firebomb on the roof of a ranger station in Oregon's heavily logged Willamette National Forest. A few months later, in a letter to the forest supervisor, ELF announced an alliance with the long-established ALF. "Leave the forests alone," the letter read, "and no one gets hurt."

The distinctions between the two groups are blurry at best. "I don't think [ELF and ALF] were ever really separate," says longtime ALF activist Rod Coronado. Their members often come out of the same anarchist ranks that marched on Seattle during the 1999 World Trade Organization meetings. Lately this cross-pollination has spread to the crop-crushing underground, which includes over a dozen groups that share an affinity for monikers seemingly cribbed from thrash metal bands—Minnesota's Bolt Weevils, Hawaii's Menehune, Wisconsin's Seeds of Resistance—and count radical animal and eco-activists as sympathizers. For instance, ALF press spokesman David Barbarash, a 36-year-old activist based in Vancouver, British Columbia, also works with Genetix Alert, a group that uses the Internet to publicize direct action against genetic engineering companies.

With its 1998 arson attack on the Vail ski resort, a Christmas 1999 firebombing of a Boise Cascade office in Monmouth, Oregon, and the December 31, 1999, torching of a genetic engineering research office at Michigan State University's International Institute of Agriculture, ELF has effectively become the most destructive group on the radical fringe. And although Earth First! has renounced monkeywrenching, members are often careful not to denounce ELF's actions. When asked about their relationship with the ELF "elves," Andy Caffrey, who operates an Earth First! press office in northern California, said, "That's not an appropriate question for Earth First!. Some people think a more militant approach is justified, but the vast majority of Earth First!ers think [ELF] is totally irrelevant to Earth First!."

Above all, the thing that makes ALF and ELF so formidable is their lack of organization. The "leaderless resistance" model was pioneered in America by right-wing Christian Identity terrorists in the 1980s. "It's created some real problems for law enforcement," says Brent L. Smith, a professor of criminal justice at the University of Alabama at Birmingham and the author of Terrorism in America. As David Tubbs, the FBI's former head of counterterrorism, once remarked, proving a case against ALF is "like trying to grab Jell-O."

Clausen knows from Jell-O. He stayed on that ALF case long after the trial (Mrs. Pickell was not convicted). Through arrest reports and newspaper articles, he followed one activist as she road-tripped across the country from Oregon to California to Minnesota. In October 1997, nearly a year after the first Bon Marché protests, ALF activists went on a rampage in central Wisconsin, releasing 3,600 minks from three fur farms and causing $200,000 in damage. Two suspects were ultimately indicted in the case. Both had ties to the earlier Bon Marché protests. Did Clausen's information lead the cops to the suspects? Probably not. The ALF activists revisited the crime scenes, and alert local farmers wrote down their license plate number. Did his information help? Possibly. Barry Babler, an FBI special agent who worked the case, recalls Clausen calling up to talk about the crimes after the suspects were nabbed. "He seemed to know what he was talking about," says Babler, "but I can't say his information was crucial."

This is why radical environmentalists who don't loathe Barry Clausen often laugh at him. They believe, unlike Ron Arnold, that the cupboard is bare. "He called me up once just to tell me that he wanted me to know that he knew who set the Burns BLM fire," says ELF spokesperson Craig Rosebraugh, referring to the November 29, 1997, blaze in central Oregon, claimed jointly by ELF and ALF, in which 600 wild horses and burros were released. "Am I worried about his database? No. If he had anything, there'd have been arrests years ago. And there's been nothing."

Well, very little. ALF activists are tough to convict, but they aren't untouchable. In 1994, ALF spokesman Barbarash spent three and a half months in jail for a raid on a University of Alberta medical laboratory. Rod Coronado, 34, served three and a half years in state prison for torching another Michigan State University agricultural research lab. Police have yet to charge a suspect in any ELF-related case, but they may be coming close. In February, federal agents in Portland raided Rosebraugh's home and seized his possessions, including his computer hard drive, in an attempt to find evidence linking him and other activists to the Vail fire.

Not all activists share Rosebraugh's dismissive attitude toward Clausen. At last year's Earth First! Round River Rendezvous in the San Juan Mountains of southern Colorado, Clausen talked to a number of people before being recognized and shooed away. Several members of the Biotic Baking Brigade, the pie-launching group famous for the 1998 creaming of San Francisco Mayor Willie Brown, happened to be attending the gathering. Seizing the moment, they grabbed their tins and tailed Clausen to the nearby town of San Luis. "As Clausen snitched away on a pay phone," recalled "Agent Apple" in a subsequent issue of Earth First! Journal, "the pie militants launched a delicious salvo of edible missiles: chocolate, banana-marshmallow and lemon cream. Triple sploosh!"

"As long as spies lie," warned a BBB operative, "the pies will fly!"

"I knew something like that could happen," Clausen says of the splooshing. "I chased 'em and got their plate number and ran it, so I know who it was." He declines to name his attackers.

The warnings aren't always so comical. Last August, Clausen received an envelope stuffed with razor blades and a warning from the Justice Department, an ALF splinter group: "You have been targeted. You have until autumn of the year 2000 to get out of the bloody fur trade. If you don't heed our warning, we will turn your violence back upon you." A schematic drawing of a poster tube bomb was attached.