He's being charged as an adult. Colorado law allows for this under certain circumstances, which include consideration of the type of offense and the extent of any prior criminal history. The law intends this allowance for a reason.
Being 17 didn't hinder him from being fully prepared to commit an organized brutal murder that involved dismemberment of his victim and the hauling of the victim's torso to one area, the hiding of other remains in the same home in which his mother and sibling reside, some serious clean-up somewhere along the way, and the neat depositing of the victim's personal belongings. Whether he's telling the truth about how and when he actually killed this child or not, he made a series of decisions over a period of time that, from where I'm sitting, are not a product of off the cuff adolescent reasoning.
He spent time on this crime. He found ways to not only find and abduct a victim, subdue her, tie her (this means he had a means to do so at his immediate disposal), dismember her body, separate parts he wanted to dispose of from parts he wanted to keep in his close proximity, he folded articles of clothing, placed them in the victim's pack, and left it upright on a residential sidewalk where it was sure to be noticed. Note, he didn't toss her backpack with items she had in it, as the pack existed when he encountered her - rather, he controlled what LE found in that pack and how it appeared when found. Putting clothing only he could have removed from the victim in the pack that was part of the LE description of what the public should be on alert for is, in my opinion, a thoughtfully considered behavior. A profiler, whose remarks were in MSM news articles, said it sent the message, 'I did this, I'm the one you're looking for.'
He's been described in the MSM by a friend as being "arrogant" and he was also described as "brilliant." He confessed to his mother, then confessed again to LE in some detail, yet, in my view, either told a tale that isn't entirely plausible, or, the police aren't filling in all the blanks just yet. It makes no sense to me that he simply grabbed a kid, quick hog-tied her in the car, then immediately strangled her, then transported the torso (where's the part about how she ended up "not intact"?) to the dump site, dropped off the backpack on a sidewalk, standing it up, then went home and hid the rest of her remains in the crawlspace. Just like that? Boom?
And if he did kill her that quickly, in my view, it was because he ultimately wanted a body to control and perform further acts of brutality on for his own enjoyment, and that requires goal setting and a highly organized skill set.
I worked with some scary people while doing casework in a non-profit social services environment, and what linked the sociopaths together and separated them from the rest of my clients, was the desire to talk about things that interested them in a manner that manipulated the listener and drove the conversation in a direction that was satisfying to the storyteller. On the surface, it appears this individual gave it all up because he was essentially already caught, and that may be so, but at another level, I don't buy that he's finished with exerting his control over what LE does and believes about him. He may be telling most of the truth, but I suspect he is enjoying feeling some measure of control over the disclosure of some of the details of what he's done. Frankly, his remark about "distracting" LE says to me he's been closely watching the coverage since its been theorized in the media that the backpack could be a distraction. His claim sounds like a manipulative parroting of that. Just my opinion.
For a predator, it's not just about the killing. It's about the savoring of the entire crime and re-living it, and conveying information in a controlled manner that is always about drawing attention to the perpetrator and his 'power' or skill. It's never about the victim or the families or anyone else. Victims are simply pawns in a predator's endgame.
He may only be 17, but what we know so far about him strikes me as someone who's proud of his accomplishments. He was described as "cooperative" with the police after he turned himself in at his home.
This individual also had the nerve to try and overcome an adult woman with a chemical soaked rag and he wasn't deterred by his failure. He simply sorted out a weaker victim in his culling of the herd.
In my view, he's no less cunning or tactically shrewd than any other predator simply because he happens to be in an adolescent body.