A Mississippi man accused of sending poison-laced letters to President Barack Obama, a senator and a judge is scheduled to appear at change-of-plea hearing Friday, NBC News reports. James Everett Dutschke, from Tupelo, Miss., has denied sending letters containing the deadly substance ricin. In November, while Dutschke was behind bars, he was charged again with attempting to get someone to send more letters containing the substance on his behalf. Court documents show the hearing is set to take place at a U.S. District Court in Oxford, Miss., at 1.30 p.m. local time on Friday. Dutschke previously has pleaded not guilty to all the charges.