(CNN) -- The Colorado teenager accused of killing 10-year-old Jessica Ridgeway pleaded not guilty Friday on all counts he is facing, a court spokesman said.
Austin Sigg is accused of strangling young Jessica, dismembering her and placing some of her body parts in a crawlspace under his family's home.
Sigg, who lived about one mile from Ridgeway family, was 17 at the time of the killing and was charged as an adult. He is now 18.
Colorado state courts spokesman Rob McCallum said that Sigg, who faces 18 criminal counts, was arraigned and pleaded not guilty in court Friday.
In addition to murder, sexual assault, kidnapping and other charges tied to Jessica's case, Sigg has also been charged with attempting to kidnap, sexually assault and kill a female jogger last May.
Police found parts of Jessica's body at a park five days after the bespectacled blonde girl disappeared while walking to Witt Elementary School on October 5, 2012.
A break in the investigation came when Sigg's mother called 911 and handed him the phone. Sigg, police said, confessed.