I have to agree with you, I think JM also told them where Hannah was. Just a feeling I have, with nothing to back it up. That house where Hannah's remains were found behind, from the moment I saw it, creepied me something awful. I have no idea what kind of material is on that house, I see some is brick. The cottage on the property isn't as creepy. I'm curious how long a renter stayed when renting that property, and also wonder if anything bad also happened on that property. If I were looking to rent or own a place around there, I wouldn't attempt to even go on the driveway to look around. Just really bad feelings coming from there, and do have to wonder if maybe there are other victims on the property?
Normally when a suspect confessed to a crime and there is a body to be found, the suspect is taken to the location to show police where he put the body. In this case, searchers were looking in the park, and at the end of the search they decided to check an abandoned property neighboring the park. That's where they found a body.
It seems clear that the body was located by searchers that made a decision to check a property, and not a result of the suspect telling police where he put the body.