A Mississippi martial arts instructor arrested early on Saturday was charged with possession of the biological agent ricin and with attempting to use it as a weapon, the US Department of Justice announced.
James Everett Dutschke, age 41, was arrested following searches of his home and a former business as part of an investigation into ricin-laced letters sent to President Barack Obama and two other public officials.
Dutschke was taken into custody by FBI agents at his Tupelo home in the early hours of Saturday morning, FBI spokeswoman Deborah Madden said in a statement.
If convicted, Dutschke faces maximum possible penalties of life imprisonment, a $250,000 fine and 5 years of supervised release.
Dutschke is expected to appear in the United States District Court in Oxford, Mississippi, on Monday.
US prosecutors dropped charges on Tuesday 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.
Prosecutors said at the time that the investigation had "revealed new information" but provided no details.
Dutschke's attorney, Lori Basham, did not return calls seeking comment but she told Reuters earlier in the week that her client denied having anything to do with the ricin letters.