Child sex murders usually fall into two distinct groups, imo - those who plan for it, and those who take advantage of an opportunity.
The timing of Alanna disappearing, where she disappeared, the randomness of using belts and tape - all suggests opportunity.
I don't think any of this was planned. I don't think the perp was a serial who got up one day and went hunting.
I think it was someone Alanna felt vaguely familiar with, even if it was someone's visiting son/nephew/plumber, that she found at home instead of who she'd come to visit.
For these reasons I hope for an arrest very soon, in fact I bet they've got a list of potentials, however if the perp has no history, all the DNA in the world isn't going to help LE identify him/her.
The relative may also be covering for the perp, or may not even know the perp visited that day as they were out at the time. Endless scenarios fit.
Maybe it will end up a case of trailing him until he drops a cigarette butt...! As someone mentioned earlier.
:moo: