Portland, Ore. ? Three more people pleaded guilty Friday to being part of an ecoterrorist cell that planted fire bombs across the West.

The trio are accused of trying to stop logging, wild horse roundups, genetic engineering of plants, sport utility vehicles sales and expansion of a ski resort into endangered lynx habitat.

The pleas in U.S. District Court brought to six the number of people indicted on conspiracy and arson charges. They have agreed to cooperate with the investigation into 16 attacks that occurred from 1996 to 2001 and caused more than $20 million in damage in Oregon, Washington, California, Wyoming and Colorado.

Those pleading guilty were Portland disc jockey Chelsea Gerlach, 29; Stanislaus Meyerhoff, 29, Gerlach’s high school classmate; and Susanne Savoie, 29, an employee at a group home for the developmentally disabled.