Ricin

Federal authorities have arrested Paul Kevin Curtis, 45, for allegedly sending letters containing the deadly poison ricin to President Obama and Senator Roger Wicker (R.-Miss.) earlier this week.

1:10 p.m. (EST): A third letter, this one sent to Senator Joe Manchin (D.-W.V.), has been found to contain ricin. 12:45 p.m. (EST): FBI spokesman Paul Bresson has confirmed that the substance found in the letter to the president was ricin. The Secret Service says that a letter containing a suspicious substance and addressed to President Obama was received on Tuesday at a White House mail facility.