(CNN) - The ricin-tainted envelope intercepted at a Washington mail facility was addressed to Republican Sen. Roger Wicker of Mississippi, CNN reported Tuesday night.
The senator has been assigned a protective detail following the discovery, according to a law enforcement source.
But who is Wicker?
The junior senator from Mississippi, Wicker, 61, was first appointed by former Republican Gov. Haley Barbour to the U.S. Senate in December 2007 after the resignation of then-Sen. Trent Lott. He was then won a special election for the seat in 2008 and won re-election in 2012 to a second term.
Before joining the Senate, he held elected office as a U.S. representative in the House from 1995 to 2007. Before that, he served in the Mississippi Senate.
Wicker was one of 16 GOP senators who voted to end a filibuster against a gun control bill on Thursday. He was also one of the 12 Senate Republicans who dined with President Barack Obama at the White House last week.
"I know Roger well," House Homeland Security Chairman Michael McCaul said on CNN's "Erin Burnett OutFront." "He's a nice guy. I don't know why anybody would want to do this to him."
Wicker serves as deputy whip in the Senate, alongside Senate Minority Whip John Cornyn of Texas.
He sits on multiple Senate committees, including Armed Services; Budget; Commerce, Science, and Transportation; and Environment and Public Works; and the Joint Economic Committee.
Born in Mississippi, Wicker served in the U.S. Air Force from 1976 to 1980 and later was in the Air Force Reserve until 2004.
When his state was struck by Hurricane Katrina, the then-congressman worked against some in his own party to bring more federal funds to the area.
He's known as a staunch opponent of Obama's policies, especially health care reform, and has an A+ rating with the National Rifle Association.
He has three children with his wife, Gayle, and resides in Tupelo, where he sings in the choir at First Baptist Church Tupelo, according to his Senate website. He graduated from the University of Mississippi, where he also earned his law degree.
Postal workers started handling mail at a site off Capitol Hill after the 2001 anthrax attacks that targeted then-Majority Leader Tom Daschle and Vermont Sen. Patrick Leahy, among others.