A 67-year-old Tucson man was sentenced to 10 years in prison Monday for having a sexually explicit relationship online with a teenage girl.

Gary Duane Keith pleaded guilty to one count of sexual exploitation of a minor under the age of 15 and one count of unlawful age misrepresentation.

Pima County Superior Court Judge Casey McGinley scolded Keith at the sentencing hearing, saying the crimes had forever altered the young victim’s life.

In June, police in Rochester, Minn., contacted Tucson police after the mother of the victim discovered emails and texts her daughter had received.

The mother was concerned because of the graphic nature of some of the exchanges, including pornographic videos depicting prepubescent children.

Police in Minnesota traced the messages to a Tucson address belonging to Keith, where Tucson police later served a search warrant.

Keith used a false identify to communicate with the girl, claiming he was another girl named Sara.

In addition to prison, Keith must serve lifetime probation and register as a sex offender.

Patrick McNamara