Investigators said Christopher Lee Carlson was indicted on two criminal counts arising out of an investigation into the mailing of about 100 envelopes containing white powder.

The letters, postmarked in Portland, Ore., so far have all tested negative for toxic substances, the U.S. Attorney's office in Portland said.

A federal grand jury indictment returned Friday in Portland charged Carlson, described as being from the Portland-Vancouver, Wash., area.