Sean Williams, a former Johnson City business owner facing multiple child pornography charges, will be back in Greeneville’s federal district court Dec. 21 for an arraignment on a charge related to his Oct. 18 escape from a jail transport van.A judge will also hear a motion from Williams’ appointed attorney, Bryce McKenzie, at the 2 p.m. hearing. McKenzie has filed a sealed motion to withdraw as Williams’ appointed attorney. If the judge grants the request it will be the second time for a change in legal representation for Williams.