Colin Mulvany / AP
During the execution of a search warrant, members of the Joint Federal Haz-Mat Team, FBI and local law enforcement gather in front of the Osmun Apartments near the intersection of First Avenue and Oak Street in the Browne's Addition neighborhood of Spokane, Wash., on Saturday, May 18, 2013
SPOKANE, Wash. -- A 37-year-old man was arrested Wednesday after a pair of letters containing the deadly poison ricin were discovered in Washington state last week.
A grand jury indictment accuses Matthew Ryan Buquet of mailing a threatening communication to U.S. District Judge Fred Van Sickle at the federal courthouse on May 14.
The indictment did not say anything about ricin. However, the U.S. Postal Service said last week that two letters were discovered — one addressed to the courthouse and the other to the downtown post office — and they contained ricin in a crude form that did not immediately pose a threat to workers.
Buquet appeared in federal court in Spokane after the FBI said agents arrested him Wednesday afternoon. He pleaded not guilty.
If convicted of mailing a threatening communication, he could face up to 10 years in prison.
Ricin is a highly toxic substance made from castor beans. As little as 500 micrograms, the size of the head of a pin, can kill an adult if inhaled or ingested.
There were no reports of illness connected to the Spokane letters.
Investigators in hazardous materials suits spent most of Saturday executing a search warrant at a three-story apartment building in downtown Spokane. Witnesses reported that agents escorted a man from the building.
The Spokane investigation comes a month after letters containing ricin were addressed to President Barack Obama, a U.S. senator and a Mississippi judge. A Mississippi man was arrested in that case.