Byline: Derek Hawkins

In the pre-dawn hours of February 28, 1992, a makeshift bomb detonated in the first floor office of a prominent animal science professor at Michigan State University. The explosion and the resulting blaze injured no one, but spread into two neighboring workspaces before firefighters put it out.

When the smoke cleared, more than three decades of research, some of it unpublished, had been reduced to ash. In addition to the lost data, the fire caused more than $1 million in property damage.

The Animal Liberation Front, an extremist animal rights collective, immediately claimed responsibility. In a news release, the group said it had targeted the office because researchers had conducted cruel experiments on minks.

Investigators said all signs pointed to the group's spokesman, Rodney Coronado, as the person responsible. The 26-year-old activist was in Michigan at the time of the bombing and was believed to have participated in similar acts of sabotage in other states. He had gone into hiding shortly after the attack.

It took 14 months, but authorities eventually found Coronado, who is part Pascua Yaqui tribe, living on a Native American reservation in Arizona and arrested him. Facing 50 years in prison, he pleaded guilty to aiding and abetting arson in exchange for having other charges dropped. In 1995, he was sentenced to four years and nine months in prison.

Despite his plea, Coronado long insisted he wasn't behind the bombing. He took the plea deal because he didn't think he could win the case, he said at the time. He conceded that he was in Michigan during the bombing, but only in his capacity as Animal Liberation Front's spokesman.

But in an interview Thursday with the Lansing State Journal, Coronado came clean: he alone was responsible for the attack.

"There are no looming criminal charges against me," he said of his decision to admit involvement. "I'm as free as any person in this country can be."

For Coronado, now 50, the confession seems to be part of a broader change of heart he has experienced as he has grown...