Bismarck, N.D. (AP) A Minnesota man has been sentenced to two years in federal prison for attempted sex trafficking of a child in North Dakota. U.S. Attorney Tim Purdon said Tuesday that 42-year-old Justin Mattson had been sentenced. He was charged in November 2013 after responding to an online advertisement to purchase sex from a teen. Authorities had posted in the ad as part of an online sex trafficking sting. Mattson agreed to pay $150 for a sex act with a person who he believed to be a 13-year-old girl. An affidavit says he admitted to the crime. Mattson was one of 14 men arrested in two stings in the western North Dakota oil patch in October and November.