Authorities dropped charges Tuesday against the man they had accused of sending ricin-laced letters to the White House, a U.S. senator and a county judge as the FBI appeared to turn its attention toward his longtime antagonist in a small-town Mississippi feud.

A federal magistrate judge directed that charges against Paul Kevin Curtis, 45, be dismissed because “the ongoing investigation has revealed new information,” according to his written order. The charges were dropped without prejudice, meaning that they could be reinstated.

But Tuesday afternoon, the FBI was searching the Tupelo, Miss., home of James Everette Dutschke in connection with the ricin case. Dutschke said he is innocent and does not know anything about the ingredients for ricin.