The FBI is investigating after letters containing white powder told recipients to "take a deep breath" of Anthrax and threatened to "finish off the survivors with a hail of bullets".

Letters were sent to 6th district candidate Karen Handel's home, five of her neighbors, and at least two media outlets including 11Alive News. Nine other letters were intercepted by the U.S. Postal Service before they were delivered.

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The substance tested in more than a dozen letters was determined not to be Anthrax, and tested negative for any known hazard. The substance sent in the letter to 11Alive was identified as baking soda.The FBI vowed additional testing would be conducted "out of an abundance of caution"