A federal grand jury indicted a Sacramento man Thursday on 13 charges related to a series of anthrax scares across the country that turned out to be hoaxes.

The indictment accuses Marc Keyser, 66, of mailing threatening packages to several media outlets, businesses and Rep. George Radanovich, R-Calif. It charges Keyser with 10 counts of hoax mailings and three counts of mailing threatening communications.

Twelve of the charges each carry a maximum sentence of five years in prison. Mailing a threatening letter to Radanovich's office carries a possible 10-year prison term because he is a congressman.

Keyser, who was arrested Oct. 29, has yet to enter a plea and remains free on $25,000 bond.

Prosecutors say the mailings contained a computer disk labeled "Anthrax Shock and Awe Terror" and a packet of a grainy substance with a biohazard symbol and the words "Anthrax sample." In many cases, newspapers reported that the substance turned out to be sugar.

Some of the packages had Keyser's return address, and agents found 11 more packets when they searched his car, according to the federal complaint filed in the case.

Reached Thursday at his home, Keyser said he believes the nation has become lax about the threat of terrorism and said the mailings were "an act of conscience."

"I feel we are just as unprepared and vulnerable as ever. The nation is in a state of denial," he said in a telephone interview. "I have taken a stand. I have warned the nation."

Keyser's attorney, Assistant Federal Defender Rachelle Barbour, did not return a telephone message Thursday. Keyser's next scheduled court appearance is Nov. 19.

Prosecutors say the harmless packages created a public danger by diverting emergency workers and investigators and by causing anxiety and disruption.