Suspicious letters were sent to U.S. Senator Roger Wicker of Mississippi, President Barack Obama and a state judge about a week ago. The letters contained a substance that tested positive for ricin, a poison.
Paul Kevin Curtis was arrested last week on suspicion of sending the letters and pleaded not guilty. He was released Tuesday from jail on bond. Officials then announced that charges against him had been dropped. The ongoing investigation revealed new information, according to an assistant U.S. attorney.
No immediate explanation was given from authorities about the release. Conditions of the bond were sealed by the court.
The charges were dismissed without prejudice, which means they could be re-instated if prosecutors so choose.
"I respect President Obama," Curtis said to reporters. "I love my country and would never do anything to pose a threat to him or any other U.S. official."
FBI agents meanwhile searched another man's home. Everett Dutschke told The Associated Press the FBI searched his home in Tupelo Tuesday in the ricin case. Dutschke's house was also searched last week. Dutschke has maintained his innocence in the case.
FBI Agent Brandon Grant has testified that searches last week of Curtis's vehicle and house in Corinth, Miss., found no ricin, ingredients for the poison, or devices used to make it. A search of Curtis's computers found no evidence he researched making ricin. Authorities produced no other physical evidence at the hearings tying Curtis to the letters.
Curtis was arrested last Wednesday at his house in Corinth, Miss., and charged with sending the ricin-laced letters, the first of which was found April 15.
On Tuesday, people in hazmat suits were seen going in and out of Dutschke's house on a quiet block in Tupelo. Investigators from the FBI, U.S. Marshals Service and U.S. Capitol Police were seen outside the house. Dutschke said he counted at least 30 law enforcement agents.
Dutschke has maintained his innocence and says he doesn't know anything about the ingredients for ricin. He said agents asked him about suspect Paul Kevin Curtis, whether Dutschke would take a lie detector test and if he had ever bought castor beans, which can be used to make the potent poison.
Dutschke said his attorney wasn't with him and he didn't know whether he was going to be arrested.
Dutschke said that he knows Curtis but that the two had a falling out. Dutschke said the last contact they had was in 2010 when Dutschke threatened to sue Curtis for saying he was a member of Mensa, a membership group for people with high IQs.
After charges were dropped against Curtis, Dutschke said: "I'm a little shocked."
The Associated Press contributed to this report.