A 79-year-old man who was sentenced to prison for molesting a six-year-old Casper girl has died in prison. The Wyoming Department of Corrections says Arlo Ernest Benbo died Monday at the Wyoming Medium Correctional Institution in Torrington after a lengthy illness.  Benbo, a former truck driver, was sentenced in October of 2009 by District Judge Scott W. Skavdahl to 12 to 20 years for second degree sexual abuse of a minor. Benbo was arrested after the girl's mother said she saw him inappropriately touch her daughter. After speaking with the girl, the mother called the police.