(CNN) -- Charges against the Mississippi man accused of sending ricin-tainted letters to President Barack Obama and other officials were dropped Tuesday, U.S. Attorney Felicia Adams said, citing "new information" that has been uncovered.
Authorities now are investigating whether someone may have tried to falsely implicate Paul Kevin Curtis, according to a law enforcement source, speaking to CNN on condition of anonymity.
Curtis said he wants to "get back to being normal" after being falsely accused.
"This past week has been a nightmare for myself and my family," he said. "My mother has suffered as well as my children."
Tuesday, while addressing the media, Curtis said at first he didn't even understand the charges. "When you've been charged with something you just... never heard of ricin or whatever. I thought they said rice, so I said I don't even eat rice."
Curtis, an Elvis impersonator from Corinth, Mississippi, was arrested April 17 and charged with sending a threat to the president last week after letters containing the poison triggered security scares around Washington.
Curtis' attorney, Christi McCoy, said her client has been framed by someone who used several phrases Curtis likes to use on social media.
The letters read, in part: "To see a wrong and not expose it, is to become a silent partner to its continuance."
They were signed "I am KC and I approve this message," a source told CNN.
They each had a Memphis, Tennessee, postmark and no return address.
McCoy said she was sure someone else was to blame.
"I do believe that someone who was familiar and is familiar with Kevin just simply took his personal information and did this to him," McCoy said. "It is absolutely horrific that someone would do this."
Curtis had been accused of sending letters containing "a suspicious granular substance" to Obama; Sen. Roger Wicker, R-Mississippi; and Sadie Holland, a Justice Court judge in Lee County, Mississippi. The FBI said the substance tested positive for ricin, a toxin derived from castor beans that has no known antidote.
The FBI said no illnesses had been found as a result of exposure to the toxin.
FOX 8 contributed to this report.