A letter addressed to President Obama containing a substance that initially tested positive for the toxin ricin was intercepted Tuesday by authorities at a remote White House mail screening facility, according to the FBI, The Washington Post reports.
The letter follows the discovery Tuesday of a ricin-laced letter sent to Sen. Roger Wicker (R-Miss.) and came as authorities were investigating suspicious packages in and near the offices of members of Congress.
Edwin Donovan, deputy assistant director of the U.S. Secret Service, did not identify the substance. However, he said the Secret Service is working closely with the U.S. Capitol Police and the FBI.
The substance was detected at a facility run by the Secret Service, Donovan said.
A law enforcement official with knowledge of the matter said the letter to Obama was intercepted in Anacostia, at a facility where all White House mail is initially screened.
It was then sent to a military installation in Maryland where it also failed initial screening for the poison.
Confirmation of ricin can take 24 to 48 hours, depending on the method of testing.