Kelli Bordeaux, in NC, was missing for a long time. Her family members all live out of state. After some time, a PI got involved in the case. Up until then, and afterward, a small group of people searched endlessly for Kelli.
In the meantime, the PI carefully and repeatedly approached the suspect (a sex offender who was sent back to prison for non-registration of change of address) after he was released from prison. The PI kind of befriended the suspect. All along Kelli was buried on private property. Whoever owns the property refused searches stating liability concerns.
If the story of how Kelli was found is accurate, the PI convinced the suspect to reveal Kelli's location. The killer led the PI there and then the PI called LE.
The difference in Kelli's case is the murderer (then, suspect) had no support in the way of sustenance which allowed the PI to befriend him by offering him a meal, a ride or other small favors.
The reason I'm posting this example is to point out the private property obstacle. If EA or others (if LE decides others are involved), have access to private property, I hope LE figures out a way to search there.
In Kelli's case, her killer just took advantage and went on the property illegally. I don't recall reading he was connected to the property owner in any way. Still, I can't reconcile why the owner didn't arrange to search his own property considering he wouldn't allow the volunteers to search.