If they have been having sightings for a decade or more and they are supposedly breeding, there would be kill sites, buried kill, scat, strong urine smell, tufts of hair and unless cats learned to fly lately, tracks. It certainly wouldn't take a decade or more to find a set of tracks. At least I wouldn't think that it would.
As far as identifying a track, by looking at a photo of a single track, you could probably indentify the animal that made the track, but all of the particulars like length of stride, size of the track, depth of the track, the soil conditions it was found in and whether or not weather and time had deteriorated the sign around the track, wouldn't really be known.
It's easy to make it appear like an animal left a track or even a few, but getting a string of them put together, to where a tracker could say that the animal came from there and went to there, would be very difficult. It would take someone that is experienced in tracking, to fool a tracker and any tracker worth his/her salt would spot the phony right away. Which can't always be done from a photo that depicts a single track.