SACRAMENTO, Calif. (AP) - Three more newspapers have received letters allegedly from a radical environmental group claiming responsibility for firebombs planted at two Northern California construction sites.
Letters purporting to be from the Earth Liberation Front promised more actions "every few weeks." The letters were received this week by the Auburn Journal, the Sacramento Bee, the Roseville Press Tribune and the Lincoln News Messenger.
Five firebomb-type devices were found by a construction crew working in the office building earlier this month. The devices were disarmed, but investigators said they were capable of causing extensive fire damage.
FBI investigators confirmed that the devices were similar to those found in late December in three homes under construction in Lincoln.
The FBI says the Earth Liberation Front, or ELF, has caused more than $100 million in damage since 1996, including an arson at a five-story condominium under construction in San Diego in August 2003 that caused $50 million in damages.
The letters say ELF's goal was to cause economic damage to the Lincoln developer and make a symbolic statement against suburban sprawl. The Auburn office building was targeted as "a statement against work and the horror of the (cubicle)."
The FBI, which is investigating the crimes with local agencies, said last week it believed the incidents were the work of eco-terrorists.
"It's a serious matter," FBI agent Karen Ernst said. "The task force is looking at least eight devices that were fully capable of causing not only substantial property damage, but possibly injury to the construction workers."
Officials also have warned that eco-terrorism attacks appear to have increased in recent years, and that the attacks have become more bold.
"Certainly, eco-terrorism crimes are becoming more frequent and fierce in the United States," said Kelly Stoner, director of stopecoviolence.com, an Oregon-based group formed three years ago by companies and individuals who have been victims of such acts. "We've seen a definite uptick in such crime."
Law enforcement and experts say it is difficult to target members because anyone who acts in the name of ELF or the Animal Liberation Front, a related group, is considered a member.