The link below includes the infamous interview with SM. The quote comes from the same link.
I find it easy to speculate about that interview, but I'm not sure there's much there actually. I see a young woman, hardened, and now angered by accusations and threats. Yeah, maybe she doesn't come across as being a loving SM, but FYI, not all SM's, or SD's for that matter, get along with their SK's. I'd speculate most, but certainly not all, SM's and SD's have strained relationships with their SK's.
Unless someone can post up a link that shows LE is looking at possible murder, or has named a POI regarding that, I'm going to have to go with speculation that Gannon ran away, and is either deceased somewhere within a mile or two of home....or possibly, he arranged to be picked up/was abducted by someone and is out of the area.
Another thought I had is that SM may know the truth, but was not directly involved, and is covering up for someone, or, Gannon suffered an accidental death that SM is attempting to cover up. ALL SPECULATION!!!
Assuming the following quote is truth, then LE has information that leads them to believe Gannon ran away.
"Since the beginning, the El Paso County Sheriff's Office has said they believe Gannon ran away, telling 11 News they obtained information early in the investigation that led them to think this. 11 News asked a spokesperson with the office Thursday morning if that was still the case and was told it was.
"We have no information or evidence to change it at this point," said Deborah Mynatt."
ENDANGERED: 11-year-old Colorado boy not seen for days, stepmom speaks with 11 News and sheriff's office asks for volunteers