CORINTH, Mississippi -- The FBI announced that at approximately 6:15 p.m. EDT on Wednesday, FBI special agents arrested Paul Kevin Curtis at his residence in Corinth, Mississippi. Curtis is the suspect believed to be responsible for the mailings of the three letters sent through the U.S. Postal Service which contained a granular substance that preliminarily tested positive for ricin. The letters were addressed to a U.S. Senator Roger Wicker (R-MS), the White House, and a Mississippi justice official.
The arrest resulted from an investigation conducted by FBI Joint Terrorism Task Force, the U.S. Postal Inspection Service; and the U.S. Secret Service after a letter addressed to President Barack Obama contained a granular substance that preliminarily tested positive for ricin. The envelope was immediately quarantined by U.S. Secret Service personnel, and a coordinated investigation with the FBI was initiated.
The FBI says that any time suspicious powder is located in a mail facility, field tests are conducted. The field and other preliminary tests can produce inconsistent results. Any time field tests indicate the possibility of a biological agent, the material is sent to an accredited laboratory for further analysis. Only a full analysis performed at an accredited laboratory can determine the presence of a biological agent such as ricin. Those tests are currently being conducted and generally take 24 to 48 hours.
The FBI says that the investigation into these letters remains ongoing, and more letters may still be received. The FBI added that there was no indication of a connection between the letters containing ricin and the attack at the Boston Marathon.