A Mississippi man has been charged over letters laced with the poison ricin sent to US President Barack Obama and two other public officials.
Martial arts instructor James Everett Dutschke, 41, was charged with possession of the biological agent ricin and with attempting to use it as a weapon.
He was taken into custody by FBI agents at his Tupelo home early on Saturday and is due to appear in court on Monday.
If convicted, Mr Dutschke faces maximum possible penalties of life imprisonment, a $US250,000 fine and five years of supervised release.
US prosecutors had earlier dropped charges against another Mississippi man, Elvis impersonator Kevin Curtis, who was released from jail after a search of his home in nearby Corinth revealed no incriminating evidence.