Twenty-five years after a firebombing at Michigan State University caused more than $1 million in damage and destroyed decades of research, an eco-terrorist has broken his silence, coming clean about his role.

“I won’t sugar coat it; we were about psychological warfare,” Rodney Coronado told the Lansing State Journal.

The attack targeted MSU scientist Richard Aulerich, who was studying the nutrition and population decline of mink—research Coronado believed was carried out for the fur industry. So Coronado, a member of the Animal Liberation Front (ALF), sneaked into the MSU building through a window, kicked down Aulerich’s door, and planted his firebomb.

“We wanted researchers like Aulerich never to know when they came to work and opened their office door whether there had been an attack,” Coronado said in his interview. “We wanted them to live in fear.”

Coronado spent four years in prison for the attack, with the court also ordering him to pay $2.5 million in restitution to MSU and other victims of the Animal Liberation Front—but to date, he has paid just $2,375, the Lansing State Journal reported.

Though the interview marks Coronado’s first admission of his involvement in the MSU attack, he has spoken before about the use of unlawful tactics. In a 2014 interview with Earth First Journal, Coronado said while he would “no longer advocate illegal activity,” if someone was “asking me more directly if I regret my illegal actions on behalf of wildlife, I’d have to say no, I don’t.”

ALF, Coronado’s organization, has operated in the United States since the 1970s, and the Federal Bureau of Investigations said in 2002 that it had “become one of the most active extremist elements in the United States.”

Activists gain ALF membership, the FBI said, by perpetrating “direct activity,” which usually means some form of criminal activity that menaces opponents or destroys their property. The group is known for being particularly skilled at arson, including using explosives.

Between 2000 and 2012, ALF and its affiliate, the Earth Liberation Front, carried out at least 100 attacks, according to statistics compiled by the National Consortium for the Study of Terrorism and Responses to Terrorism.

And a 2014 study found that, between 1970 and 2007, radical environmentalists and animal rights activists had committed more than a thousand criminal acts, including 55 bombings or other attacks using explosives, the Washington Postreported. The FBI puts that number even higher.

Last year, FBI records obtained by Muckrack showed that eco-terrorism remains a concern. A 2013 memo warned of a “recent upsurge in animal rights extremist activity in the west and Midwest,” citing “more than 30 animal releases and acts of vandalism” that occurred in nine states between May and September 2013.

— Jillian Kay Melchior writes for Heat Street and is a fellow for the Steamboat Institute and the Independent Women’s Forum.