The FBI is investigating after finding two suspicious letters headed to Capitol Hill. Authorities say letters sent to President Obama and Sen. Roger Wicker are related and are both postmarked out of Memphis, TN, dated April 8. The FBI says the substance in both letters has preliminarily tested positive for Ricin, a potentially fatal poison. Both the letters to Wicker, a Republican from Mississippi., and to Obama were intercepted at off-site mail facilities. The FBI says it is pursuing investigative leads to determine who sent the letters.