Last night a letter addressed to Sen. Roger Wicker (R-MS) tested positive for the powerful poison. There is no known connection between the ricin letters and the Boston bombings. Sen. Claire McCaskill (D-MO) said last night that there is a suspect in the first ricin letter.

Update: Fox reports that both letters were mailed on April 8, from Memphis, TN. Neither of the letters ever reached any Senate office.

Update: It sounds like we now have three ricin letters. A third one was reportedly sent to President Obama.

Update: There may be less to these ricin letters than meets the eye. After last night’s revelation of the first letter, addressed to Sen. Wicker, Sen. Claire McCaskill said two interesting things. The first is that they already have a suspect in mind. The second is that this suspect is known to send letters to politicians. It’s reasonable to deduce from that the person sends ricin-laced letters frequently. Capitol mail safety protocol ensures that they never reach their targets. This time, the letters happened to coincide with the Boston bombing. They were reportedly mailed April 8, a full week before the bombing. The safest guess at the moment, therefore, is that the letters and the bombing are unrelated.

Update: Intelwire reports–