The FBI confirms that an intercepted letter sent to Mississippi Republican Sen. Roger Wicker tested positive for Ricin at a field office.
Ricin is a biotoxin–a poison derived from the castor bean plant that can be fatal even in small doses.
The tainted letter was detected in an off-site screening process at a U.S. Post Office in Landover, Md., sources close to Wicker tell NBC News. The envelope never reached the Capitol, and at no time was Wicker or his staff in any danger, the source says.
The envelope tested positive for Ricin at both the postal facility and the FBI field office in Baltimore. False positives are somewhat common, NBC reports, and authorities will not have a full determination until further testing.
Wicker issued a statement hours later saying the matter is part of an ongoing investigation by Capitol Police and the FBI.
“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,” Wicker said. “Gayle and I appreciate everyone’s thoughts and prayers.”