I believe the GPS gives them an idea of where the person went. If this is from the vehicle, they could be searching a wide area because the GPS will stop location wherever the vehicle stops. If it’s from a cellphone that the person had on them, they could track it closer but cellphone pings are radius areas versus exact pinpoint. That’s what I understand- MOO and correct me if I’m wrong. This is just how it appears to me as a follower of many cases.