Investigators are revealing that an envelope that was suspected to contain the highly toxic poison ricin was sent to the Capitol Hill office of Sen. Roger Wicker.
Fortunately, the enveloped never made it to the Senator's office as it was confiscated at a mail screening facility. The mail-screening system was implemented in the wake of the 2001 anthrax attacks that struck the Hart Senate Office Building.
Officials have not released the names of any suspects as the investigation is ongoing, but did state that they did have a person of interest in mind.
"The person that is a suspect writes a lot of letters to members," Sen. Claire McCaskill told the Associated Press.
The letter inside contained a threat that was categorized as conveying: "You haven't listened to me before. Now you will, even if people have to die," Politico previously reported.
The envelope was sent to a lab in Maryland where further testing is under way after field tests conducted by the FBI revealed inconsistent results.
Ricin is deadliest when inhaled, with oral ingestion requiring a much larger dose, according to a Homeland Security Department handbook. It is not contagious and there is no antidote, but it is known among extremist groups for being easily produced.
Mail delivery has only been stopped to the Senate and not the House, but politicians and law enforcement personal are taking this matter very seriously, especially given the recent bombings in Boston.
"It is of concern," Sen. Angus King, I-Maine, said after learning about the incident in a briefing with other senators late Tuesday.
Officials indicated that the envelope had a Tennessee postmark and no return address. Officials connected with the case are thought to be familiar with the person believed to have sent the letter, as the person has sent other letters previously.