Washington, Apr 16 (EFE).- Security personnel guarding the U.S. Congress on Tuesday detected a highly toxic substance in an envelope sent to Republican Sen. Roger Wicker, congressional sources told U.S. media.
The daily Politico said that the letter containing the poison was addressed to the Mississippi lawmaker, who is a member of several Senate committees, including the Armed Services Committee.
When screened prior to delivery to Wicker's office, as all incoming mail to Congress is handled, the envelope tested positive for ricin, a whitish powder that can be deadly if inhaled, according to a congressional official.
The substance was found during a routine security check at the off-site facility that receives all the lawmakers' incoming mail.
Authorities repeated the test twice more and the positive result was obtained again both times. The letter was not delivered to the senator.
Sen. Claire McCaskill (D-Missouri) said that the sender was a person who has mailed frequent letters to national lawmakers, but no further details about the origin of the letter were provided by authorities.
Ricin is a poison that can be made from the residue left after processing the seeds of the castor plant to make castor oil.
The toxin can exist as a powder, vapor or in granular form, but it can also be dissolved in water or weak acid. It is a stable substance that is not affected much by extreme conditions such as very high or very low temperatures.
Wicker was appointed by Mississippi Gov. Haley Barbour in December 2007 to fill the seat vacated by Trent Lott. He then won the 2008 special election for the remainder of the term.
Before entering the Senate, Wicker served in the lower house of Congress from 1995-2007 representing Mississippi's 1st congressional district.