A 41-year-old martial arts instructor was charged with sending ricin-laced letters to President Barack Obama and other public officials following his arrest Saturday.
James Everett Dutschke was formally charged with attempted use of a biological weapon just hours after being detained at his home in Tupelo, Mississippi at 12:50 am (0550 GMT) by federal agents.
Three letters laced with ricin were discovered last week as the nation was reeling from the deadly bombing at the Boston Marathon, an eerie echo of the anthrax letters sent to public officials soon after the September 11, 2001 attacks.
The potentially lethal letters had been sent to Obama, a US senator and a Mississippi judicial officer.
Dutschke has been charged with "knowingly developing, producing, stockpiling, transferring, acquiring, retaining and possessing a biological agent, toxin and delivery system, for use as a weapon," the FBI's local field office and the US attorney's office said in a statement.
If convicted, he faces a maximum penalty of life in prison, a $250,000 fine and five years of supervised release.
Dutschke will appear before the US District Court in Oxford, Mississippi on Monday, a Justice Department statement said.
Authorities had initially arrested another man, Paul Kevin Curtis, in the case but the charges against him were later dismissed and he was released from jail.
Investigators suspected Curtis because he had written publicly about an alleged black market for the illegal sale of human body parts that he thought was being covered up by the government.
But his attorney insisted from the get-go that Curtis was framed and pointed the finger at Dutschke, who reportedly had a long-standing dispute with Sadie Holland, a Mississippi justice of the peace who received one of the letters.
Dutschke, however, insisted that Elvis impersonator Curtis had implicated him in order to dodge his own guilt.
"I guess Kevin got desperate. I feel like he's getting away with the perfect crime," he told The Clarion-Ledger newspaper earlier this week.
"It has made my family incredibly unsafe. It has put a target on us, and it was reckless and irresponsible," Dutschke added.
"The phone has been ringing off the hook, with calls and hang-ups and all sorts of horrible things."