If LE has a good idea that foul play is involved, they will stop public searches. It's not hard to contaminate evidence. LE doesn't need to spend resources rescuing searchers that get lost or hurt. They also don't need the liability. Searching for a missing person is like looking for a needle in a haystack. After a certain amount of searching, it's more productive to use evidence to lead them to a more specific search area. Was the public search organized? Did they use a gps program and submit their results, so that no area is missed? Are they trained to know what to look for? Do they know to look up. I've seen well intentioned searchers bring their kids along. Not a good idea! There is a lot more to searching than meets the eye. Oh and the perp joins the search and says he searched where the body is so no one else goes there. Or he even goes back and moves the body. Or tamper with the evidence.