(CNN) -- Austin Reed Sigg must face trial on 18 of 20 counts related to the slaying of 10-year-old Jessica Ridgeway and an attack on a jogger last year, a spokesman for Colorado's courts said Friday.
Rob McCallum made the announcement after the 18-year-old Sigg appeared before Jefferson County Judge Stephen Munsinger in a preliminary hearing. The arraignment is set for March 12; Sigg remains on no-bond hold.
The student was charged last October with kidnapping, sexual assault and murder in the death of Ridgeway, whose body parts were found in a park in a Denver suburb.
Sigg, a student at Arapahoe Community College, also was charged with attempting to kidnap, sexually assault and kill a female jogger last May.
Sigg, who lived about one mile from Ridgeway's home in Westminster, was 17 at the time of the killing; he is charged as an adult.
He was accused of strangling Ridgeway, dismembering her and placing some of her body parts in a crawlspace under his family's home.
Police found parts of her body at a park five miles away five days after the bespectacled blonde girl disappeared while walking to Witt Elementary School on October 5.
A break in the investigation came when Sigg's mother called 911 and handed him the phone. Sigg, police said, confessed.