PHOENIX (AP) -- A Mesa man has been sentenced to 12 years in prison and lifetime probation in a child pornography case. The Arizona Attorney General's Office announced Monday that 54-year-old Christopher John Clark entered into a plea agreement. Authorities say Clark pleaded guilty to downloading child pornography using a file-sharing program. They say Clark shared approximately 920 child pornography files using a file-to-file sharing website during a four-month period in 2012 and 2013. He was arrested in March and indicted by an Arizona grand jury agreement on 10 counts of sexual exploitation of a minor. As part of his sentence, Clark also will have to register as a sex offender.