I understand your question. LE has both options. However, the time it takes to search the vast deserts, ravines, mountains in this area could take the years the sheriff referred to in his recent statements. Bodies are found in these desolate areas decades after they have gone missing.
However, if you find the perpetrator(s), you at least have a chance to find your victim. You can use their capture to negotiate jail time, death penalty etc if they lead LE to the victim, whether alive or deceased. If there is more than one perp arrested, you can play one against the other.
Searches without knowledge of the general area where the victim was dropped is like trying to find a needle in a haystack.