The powders turned out to be yeast or flour, though not all letters have been fully tested, the Federal Bureau of Investigation said in a court filing made public Tuesday.

Federal authorities charged an Oklahoma man with sending hundreds of letters containing nonhazardous white powder to public officials.

Federal authorities charged an Oklahoma man with sending hundreds of letters containing nonhazardous white powder to public officials.

A suspect was arrested by the FBI’s Oklahoma City field office in connection to hundreds of suspicious letters sent to government and election offices.