A Roman Catholic priest already under investigation over a complaint of alleged child sexual abuse was arrested Friday on federal firearms charges. The Rev. Paul Gotta was charged with aiding and abetting the unlawful transportation of a firearm and the purchase of a handgun by a juvenile, the US attorney’s office said. Gotta’s attorney, Moira Buckley, declined to comment. Gotta is being held pending a detention hearing next week. Documents in the case were sealed.