Maybe this is covered in this long thread ... but from reports of the murder scene do you think this guy really killed the mom, boyfriend and brother? Reports are the boyfriend was a really big man. This Duncan guy looks slight in his build. Could Duncan have 'bought' Shasta from the person(s) that did the killing?
I have not been on this case as many here have. Just from what I DO know it's difficult to believe he committed the murders and took the kids by himself, much less held them both for this long without someone else. Hard to say, though, the guy is obviously motivated.
Reports are also that the mom and boyfriend had meth and pot in their systems, though no indication of levels. But, if they were high at the time, it would have made their murders that much easier.