Gene Palmer, a prison guard at the Clinton Correctional Facility who worked in the cell block from which convicted murderers Richard Matt and David Sweat escaped, has been arrested, officials said Wednesday. Palmer is charged with felony counts of promoting prison contraband and tampering with physical evidence, and a misdemeanor count of official misconduct. Joyce Mitchell, a seamstress at the upstate New York prison who handed Palmer frozen ground beef that contained escape tools, was arrested June 12. Palmer's lawyer told NBC News that his client will plead not guilty when he is arraigned Thursday, and that while Palmer had admitted handing off the meat, he had no knowledge of any contraband inside.