Perhaps someone has noted this already, but the ABC reported that "
Five unmarked police cars were seen travelling to the remote search site early on Tuesday".
Although not explicitly made, the suggestion seems to be that Mr Lynn may have pointed out the exact location.
Another observation that folks have made, is that police are speaking of "human remains". They are sifting the soil and there is a clip I saw in which the camera microphone caught one of the search team telling another one to be on the look out for bone.
Depending what the soil chemistry is like (i.e. the actual chemicals and amount of oxygen) and the microbes, sometimes bodies are well preserved and can be for thousands of years. In other soils, bodies decompose very quickly. You are then looking for teeth, dentures, and things like artificial hips or knees or plates used to men broken legs and arms. Hence the person waving around a metal detector (wrongly identified as a ground penetrating radar - see photos)
Ground penetrating radar.
Metal detector