A federal grand jury has added more counts to an indictment that accuses a Vancouver, Wash., man of sending threatening letters laced with white powder to Congress members.
A superseding indictment issued Wednesday charges 39-year-old Christopher Lee Carlson with 12 counts of sending threatening letters and including false and misleading information to six politicians.
Previously he was charged with sending letters to Republican House Speaker John Boehner of Ohio and Democratic Sen. Barbara Mikulski of Maryland.
The new charges involve Republican Sen. Pat Roberts of Kansas, Republican Sen. Ron Johnson of Wisconsin, Republican Sen. David Vitter of Louisiana and Republican Sen. Marco Rubio of Florida.
Carlson pleaded not guilty this week to the earlier charges. He is due in court April 5 for a hearing on whether he must remain in custody pending his June trial date.
The charges arose from an investigation into the mailing of about 100 envelopes containing white powder. The U.S. attorney's office in Portland said the letters, postmarked in Portland, have tested negative for toxic substances. The letters came to light in late February.