A 60-year-old grandfather figure was sentenced Monday to 30 years in federal prison for the sexual abuse of two girls under 12.

Jurors found Dean Earl Wilkens guilty in July of four counts of aggravated sexual abuse that took place between 2008 and December 2011, when one of the girls finally reported it to school officials.

Wilkens, a truck driver, is a resident of the Red Lake Indian Reservation. He had worked for Red Lake Builders and the Beltrami County Highway Department.

He also worked for the Goodridge and Grygla schools as an occasional bus driver.

Assistant U.S. Attorney Clifford Wardlaw asked that Wilkens be sentenced to life in prison, which he called "a just sentence for the repeated sexual abuse of multiple victims over an extended period of time."

The girls viewed Wilkens as their grandfather, Wardlaw said.

Chief U.S. District Judge Michael Davis sentenced Wilkens to the mandatory minimum term of 30 years in prison, plus supervised relief for life.