Billy Cottrell, a 23-year-old graduate physics student, was indicted for damaging or destroying vehicles at car dealerships and homes in the Los Angeles area last August, said Thom Mrozek, a spokesman for the U.S. attorney's office on Wednesday.
Cottrell, who could face life in prison, has been held without bail since his arrest on March 9. His attorney, Stephen Alexander, said Cottrell was innocent and declined further comment.
A bond hearing was scheduled Wednesday and an arraignment was set for March 29.
According to an FBI affidavit, Cottrell contacted the Los Angeles Times by e-mail using an alias and told the paper he was involved in the firebombings. The California Institute of Technology student signed the e-mails ELF, short for Earth Liberation Front, according to the affidavit. Authorities tracked the e-mails to Cottrell.
Investigators say the firebombing spree hit four car dealerships and at least four privately owned vehicles.
A fire set at one dealership destroyed or damaged 72 vehicles, mostly SUVs, and a parts warehouse. "ELF," "Fat, Lazy Americans" and "I (heart) pollution" were painted on the SUVs. Prosecutors estimate the total damage at $2.3 million.
The Earth Liberation Front has claimed responsibility for a string of arsons in Detroit, Philadelphia and San Diego, where a fire last year destroyed a 206-unit apartment complex under construction, doing $50 million worth of damage.