GRAND JUNCTION, Colo. (AP) - A teen charged with killing a western Colorado sheriff's deputy will be prosecuted as an adult.

The Daily Sentinel of Grand Junction reports ( ) that District Judge Richard Gurley ruled Thursday that Austin Holzer, who was 17 when Mesa County Sheriff's Deputy Derek Geer on Feb. 8, 2016, will be prosecuted as an adult.

As an adult, Holzer faces 40 years to life in prison for the shooting. If Gurley had chosen to prosecute Holzer as a minor, he would have faced only 20 years.