I could also add, in relation to success, that perhaps it's not necessarily finding the person responsible. In many investigations, there are multiple suspects. If there are suspects we can go to initially, and we have this information and know that they don't match the physical description, they're immediately no longer on the police list, and police are able to concentrate their investigative efforts and their resources on other areas.
So even from a very practical standpoint, for investigators to be moving in the right direction and discounting suspects has value as well, because it allows us to move the investigation forward to the more likely suspects.