Update at 6:02 p.m. ET. Charges Dropped:
Federal prosecutors have dropped charges against a Mississippi man they accused of sending ricin-laced letters to President Obama and two other public servants, according to a court order obtained by the AP.
"In a court order calling for the charges to be dismissed, prosecutors said the 'ongoing investigation has revealed new information' without providing any additional detail," Reuters reports.
Paul Kevin Curtis was released from custody earlier Tuesday.