A 70-year-old Kansas City man has been convicted by a federal judge of using a 12-year-old girl to produce pornography.The federal prosecutor says Joseph Vanhorn gave the girl marijuana and alcohol, and took took pictures of her in a trailer in the southwest Missouri town of Noel. The girl reported the incident to an official at her school who called police. Images of the girl were found on Vanhorn’s computer at his Kansas City home.