You can watch portions of it above in a newscast from Fox 31 Denver. WARNING: DISTURBING CONTENT.
Here's a partial transcript of the interrogation of Sigg, a mortuary science student who labeled his victim's organs and kept her skull as a souvenir:
DETECTIVE: So when you initially took Jessica you were actually in the back seat of your car?
SIGG: Yes, and then I zip-tied her hands and feet.
SIGG: The second I pulled her into my car I knew she was dead.
SIGG: The dismemberment was from forensic scientist class. Serial killers and the successful ones were the ones who could always make the body disappear.
And below, the previously released 9-1-1 call from Sigg, in which he admits the murder. The call originated from his mother, who handed the phone to Austin at the dispatcher's request.
That call was detailed in an arrest affidavit (scroll down for full document):