A Mississippi martial arts instructor was named in a five-count indictment charging him with mailing ricin-laced letters to President Barack Obama and two other public officials, authorities said on Monday.
The U.S. Attorney for the Northern District of Mississippi said James Everett Dutschke, 41, who was arrested on April 27, faced a maximum penalty of life in prison for threatening the president and others by mail and "possessing a biological agent, toxin and delivery system for use as a weapon."
The grand jury indictment was filed against Dutschke on Friday as authorities, in separate cases in Washington state and Texas, were investigating two other batches of ricin-laced letters sent to Obama.
The most recent case has centered on a man in New Boston, Texas, whose wife called the police to report suspicious activity, a law enforcement official said.
Dutschke's arrest came several days after U.S. prosecutors dropped charges against another Mississippi man, Paul Kevin Curtis, who was released from jail after a search of his home revealed no incriminating evidence.
The case drew widespread media scrutiny in the days after the bombing at the Boston Marathon.
The grand jury indictment against Dutschke included one count charging him with having "intentionally devised a scheme and artifice to make it appear that Paul Kevin Curtis had mailed threatening letters containing ricin to the president of the United States, a United States senator, and a Mississippi Justice Court judge."
Curtis, an Elvis impersonator, had already alleged that Dutschke attempted to frame him as part of a long-running feud.
Dutschke, who has been held without bail since waiving his right to a detention hearing, is due to appear in U.S. District Court in Oxford, Mississippi on Thursday, the U.S. Attorney's office said.