I believe the ground radar equipment is able to detect depth as well as disturbances in soil as well as shapes of objects. If that's so, then they may have detected disturbances in the ground that are slightly deeper than the actual dirt that was recently laid down. Just an idea, imo... Also, they will surely be looking for other objects other than a body in the dirt. Sometimes, when a murder victim is disposed of, many of the objects involved may be discarded with the body such as clothing, weapon(s) bullet casings, tarpaulins, bed linens, personal objects of the victim, cigarette butts, soft drink cans... murderers can be very foolish. However, I don't believe they'll find anything at this search site, Jmo.