I am fairly certain I read early on that they took soil samples from his car tires. We have many different types of soil around here and in some places they mix, making the locations easier to identify. I am no expert in soil so these are just my observations. When I lived in southern Albemarle, the farm had some red clay but also gray clay and just good "dirt." Where I am now is solid red clay (beautiful grass and trees but ugh when it is wet). East of Charlottesville is more gray than red. Etc. I wonder if they tracked down the general area of a soil match finally and then used the dogs in that area and that is where they are digging.I've wondered the same thing Daae! Perhaps LE found a shovel in his trunk when they searched and impounded his vehicle. I'm not sure how long it takes for results of soil samples but I'm wondering if this is led LE to begin digging at the undisclosed location we are hearing of. JMO.