The
letters intended for President Obama and Sen. Roger Wicker which were intercepted at mailing facilities have field-tested positive for ricin, and are undergoing lab tests to determine if the substance is manufactured ricin, or ricin-bearing ground-up castor beans.
Federal officials told NBC News that they believe they know who sent the letters, but no arrest was made because authorities were waiting for further test results.
Ricin is made from castor beans and can kill within 36 hours. There is no antidote. Some threatening letters simply contain ground castor beans, resulting in a positive field test for ricin without the concentrated poison. Results from full laboratory tests are expected in the next 24 to 48 hours.
While that was going on,
reports of suspicious packages in the offices of Sens. Richard Shelby and Joe Manchin caused partial evacuations of the Hart and Russell Senate office buildings. Additionally, letters sent to the state offices of Sens. Carl Levin and Jeff Flake had been identified as suspicious and were being analyzed. As of this afternoon, Sen. Flake's office announced there were no
dangerous materials found in those letters.
5:43 PM PT (Hunter): The FBI has announced the arrest of a 45 year old Mississippi man suspected of mailing the letters to Wicker and Obama.