Three of the Spokane-postmarked letters – addressed to Obama, a local post office and a federal district court judge in Spokane – tested positive for ricin. A fourth letter, addressed to an Air Force base, is being tested for ricin and a fifth letter, mailed to the CIA's Virginia headquarters, has not been intercepted. All five letters were postmarked May 13.
"In the unlikely event a letter fitting this description is encountered by a member of the public, the envelope should not be opened or handled and law enforcement authorities should be notified immediately," the FBI's Seattle field office said in a Thursday statement.
The Associated Press reports that Buquet, who may face additional charges, is a 37-year-old registered sex offender.
Another spate of ricin mailings appeared to be motivated by a personal feud between two Mississippi men. In April three letters postmarked in Memphis, Tenn., were mailed to Obama, Sen. Roger Wicker, R-Miss., and a Mississippi judge.
Each of the Memphis-postmarked letters tested positive for ricin and were signed "I am KC and I approve this message," prompting FBI investigators to arrest and charge Elvis tribute artist Paul Kevin Curtis. Charges against Curtis were dropped for lack of evidence. James Everett Dutschke, a fellow Mississippian who disliked Curtis, was subsequently charged with committing the crimes in an apparent bid to frame Curtis. Dutschke is in jail awaiting trial.