LOS ANGELES (AP) — A Claremont man has pleaded not guilty to federal charges that he sent threatening letters containing a powdery substance to Department of Children and Family Services offices throughout Southern California and to the Los Angeles County Children’s Courthouse.

U.S. attorney’s office spokesman Thom Mrozek says 48-year-old Martin Calvin Yarbrough Jr. was released on $25,000 bail Friday following his arraignment on 13 counts of making threats and
hoaxes.

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Prosecutors say Yarbrough sent the letters to eight DCFS offices and to the Monterey Park courthouse between November 2008 and May 2010. Each letter contained either a white powdery substance or a
bluish granular substance that was determined to be a chemical poison.

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Mrozek says there are no reports of anyone being sickened by the substances.

Yarbrough did not return a phone message.

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