A Linn County man has been sentenced to 15 years in federal prison for his conviction of charges that he produced child pornography. Prosecutors say David Russell Darr Jr. of Marceline videotaped himself engaging in sexually explicit conduct with a minor child. The crime occurred in October of 2009. Darr pleaded guilty in the case in November, and was sentenced in a St. Louis federal courtroom Tuesday. He could have been sentenced to 30-years in prison under federal guidelines. The case was brought as part of the U.S. Department of Justice Project Safe Childhood, which is a nationwide effort to combat child sexual exploitation.