WASHINGTON — An envelope addressed to Sen. Roger Wicker of Mississippi tested positive Tuesday for ricin, a potentially fatal poison, authorities said, heightening concerns about terrorism a day after a bombing killed three and left more than 170 injured at the Boston Marathon.
One senator, Claire McCaskill of Missouri, said authorities have a suspect in the fast-moving ricin case, but she did not say if an arrest had been made. She added the letter was from an individual who frequently writes lawmakers.
Shennell S. Antrobus, a spokesman for the U.S. Capitol Police, said Tuesday night that Capitol Police had been notified by the Senate mail handling facility that “it had received an envelope containing a white granular substance.”
“The envelope was immediately quarantined by the facility’s personnel and USCP HAZMAT responded to the scene,” Antrobus said. “Preliminary tests indicate the substance found was ricin. The material is being forwarded to an accredited laboratory for further analysis.”
Antrobus said called the incident a “controlled event” and said operations at the Capitol complex had not been affected by the investigation.
FBI spokesman Paul Bresson said earlier initial field tests on the substance produced mixed results and that it is in the process of undergoing further analysis at an accredited laboratory. Only after that testing can a determination be made about whether the substance is ricin, Bresson said.
Late Tuesday, Wicker released a statement acknowledging the letter and said it was sent to his Washington office.
“This matter is part of an ongoing investigation by the United States Capitol Police and FBI,” Wicker said. “I want to thank our law enforcement officials for their hard work and diligence in keeping those of us who work in the Capitol complex safe.”
Terrance W. Gainer, the Senate sergeant-at-arms, said in an emailed message to Senate offices that the envelope to Wicker, a Republican, had no obviously suspicious outside markings and lacked a return address. It bore a postmark from Memphis, Tenn.