Gotta love the media. From the way the above article reads, it appears Heather reviewed her social media messages and phone records and they inspired her to drive to PTL.
Donna Elder said they know from her GPS coordinates that she left after talking to SM from her home, and went to PTL. That premise includes the theory of a lure to PTL, implying she drove herself there to meet them and her fate.
As I recall, the other reference to PTL was after the arrests when the Solicitor said something to the effect that every indication is she drove herself there. He added something to the effect that there's nothing to indicate she didn't.
I think when your premise is "We know 'x' happened because we have no indication it didn't...and/or no indication that 'y' did
", you're really saying you have a theory.
In Heather's case, they really only know for sure that her phone traveled from her condo vicinity to the landing vicinity, and since her car ended up there, they reason she was with the phone, driving her car.
But, for all anyone knows, she could have been alone, or with SM and already gravely disabled or deceased, or someone else could have been the driver and the only one in the car, with control of her phone.
I continue to believe that the murder theory keeps the murder at PTL because it's the only location where the state can reasonably argue that all the parties were present at the same time. Theorizing beyond PTL creates problems at trial. So, I've always felt that the theory of murder at PTL is more a product of what they don't know, than what they do, and it aligns with the only timeline they have via the phone records. For that timeline to work for the state, things had to happen and be over pretty darn fast.
I don't think this lessens the probability of M's guilt. I just think it's a reflection of the fact that LE really doesn't know what the M's did, when they did it, or how they disposed of her body.
They do seem to have concluded early on that whatever was done makes Heather unlikely to ever be found. Why no elaboration on that? Because it gets into speculation after the trail of circumstantial evidence appears to have ended. The Solicitor said what they later found at the house was an extension of what they already had.
I think these two succeeded in killing her and disposing of her without a trace because they had a plan, third party help, and some luck. Not enough luck to keep them from getting arrested, but so far, enough to make their victim vanish and give their defense some ammunition in arguing, "What did they do in that fleeting time frame to end this girl's life, and how/where did they hide her if they allegedly headed back home, but no body was subsequently found on their property?"
My guess is the defense will then present some alternative scenarios of what happened to Heather.