The FBI says 66-year-old Marc Keyser was taken into custody at his home Wednesday afternoon. He is charged with three counts of sending a hoax letter.
The FBI says Keyser sent over 120 envelopes containing a packet of sugar with the label "Anthrax Sample."
So far the agency says none of the packets have tested positive for hazardous material.
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The letters were received Wednesday by two Sacramento television stations, The San Diego Union-Tribune newspaper, The Charlotte Observer newspaper in North Carolina, and the office of Congressman George Radanovich in Modesto.