JMO
If we assume that the evidence was planted, what does that tell us about the person(s) that hid the evidence. To me, it speaks of being very amateur, like they were in a hurry to dispose of her items that they had in their possession still. The items showed up pretty quick, but in different spots and on different days.
The Easter find was rumored to have been phoned in tip. Like the person wanted it to be found. So, if that rumor is true, and if the rumor that the phone call went directly to the house, then one would think that LE could trace the phone call of who made that phone call to the house. If LE identified the phone number of the called in tip, they would know who called in the tip. Maybe they did, and maybe that is why everything came to a screeching halt after the Easter find.
Even if the rumor is not true, the alleged planted evidence just seemed very amateur. Like it was thrown about in a quick fashion. What that means is the person was still local in the immediate days right after she went missing. Once they got rid of the last of the evidence, then they had nothing left, and they felt they were in the clear.
That kind of points to that they must have gotten rid of poor Holly first. So, if they were very amateiur about the evience, it also means they would have placed Holly in a very amateur spot. So, IMO, LE needs to check very obvious type places like the local lakes nearby, or shallow grave nearby. I dont think she would be too far away. I would say 90 mile radius maximum.