A California man suspected of mailing more than 120 hoax anthrax letters to media outlets was interviewed previously by the FBI after one similar mailing in 2007, but he was not charged.

Marc M. Keyser, 66, was interviewed by the FBI in January 2007 for allegedly sending a package containing a small aerosol can labeled "Anthrax," along with a compact disc, to the Sacramento News and Review newspaper, according a criminal complaint filed Thursday in federal court.

Keyser told agents then that he was using the mailing as a publicity stunt for a novel he had penned, and "to model what would happen if terrorist were to use anthrax ... to show the amount of anthrax a terrorist might spray into the air conditioning system in a shopping mall." The can did not contain anthrax.

Agents warned Keyser that he violated federal law and could be prosecuted, but they didn't arrest him. Agent Filip Colfescu said in the complaint that Keyser at the time apologized for the hoax "and told agents they should not worry, that he would not be doing it again."