PORTLAND, Ore. -- A Vancouver, Wash., man accused of sending threatening letters containing white powder to members of Congress pleaded not guilty Wednesday to federal charges.
A federal grand jury in Portland indicted Carlson earlier this month on charges that he mailed threatening letters to Republican House Speaker John Boehner of Ohio and Democratic Sen. Barbara Mikulski of Maryland.
The two counts 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.
Recipients were told that there was a "10 percent chance you have just been exposed to a lethal pathogen."
The sender wanted an "end to corporate money and `lobbying,'" an end to corporate "personhood" and a new constitutional convention. The Associated Press obtained a copy of a letter.
The FBI focused on Carlson after a Vancouver police officer told the agency about a March 4 interview in which Carlson's wife reportedly told the officer about her husband's recent emotional turmoil.
Officer Leah Supriano was on patrol that day when a dispatcher reported concerns about possible domestic violence at the Carlson home. Supriano phoned Adrienne Carlson, who said her husband had verbally abused her and left. Then she gave the officer a statement about suspicions her husband had committed a crime.
"Adrienne told me that a few months ago, Chris had talked about sending letters to members of the Senate and the media to express his frustration with certain things," Supriano reported. "About two weeks ago, they were driving in Portland ... and when they passed a post office somewhere off Stark (Street), he pointed at the post office and told her that he was worried and wondered if they had surveillance cameras."
"Oh no, you didn't send those letters did you?" Adrienne Carlson said, according to the report.
Christopher Carlson acknowledged that he did, his wife reported.
The Oregonian has reported that Adrienne Carlson told the officer her husband said he'd laced the envelopes with a mixture of celery salt and corn starch.
Investigators have recovered dozens of letters addressed to U.S. senators and representatives. The Seattle office of Sen. Patty Murray, D-Wash., said it also received one of the letters.
Some letters were sent to Congress members' district offices.
The letters bore a return address from "The MIB." According to the Vancouver police report, Adrienne Carlson told the officer "MIB" meant "Man in Black." She added that her husband was planning to send a second round of letters that would contain lye, a highly corrosive chemical used to make soap and detergents.
The listed Portland return address didn't exist.
Vancouver police forwarded the woman's suspicions to the FBI, which investigated in conjunction with the U.S. Postal Inspection Service and U.S. Capitol Police.
Carlson's mother, Rose Hatch, and his stepfather, Bryce Hatch, described him as extremely bright, The Oregonian has reported. But they said he had a somewhat contemptuous view of politicians and was disappointed that President Barack Obama had not lived up to his high expectations.