(CNN) — A 17-year-old student was formally charged Tuesday with the kidnapping, sexual assault and murder of 10-year-old Jessica Ridgeway, whose body parts were found at a park in a Denver suburb earlier this month.

Austin Reed Sigg, a student at Arapahoe Community College, was also charged with attempting to kidnap, sexually assault and murder a female jogger last May.

The charges were outlined in a 17-count accusation filed by Jefferson County, Colorado, District Attorney Pam Russell Tuesday.