The cougar I spotted 2014 was only 30 yards away and I had a guard rail to gage size, and watched it leap into the woods,...measured the jump...all that data but no hard physical evidence. I saw exactly where it went in the woods and found zero sign at all. You're lucky you've got tracks. Tell your wife I believe her. I've seen two in the 32 years working at NSWC Crane and I spend a good amount of time in the field. The sightings are rare, but they do exist.
The natural resources department here at Crane put cameras in the area for three months - nothing. They're not creatures of habit.
I've not found one eviscerated kill cache'...but I know there are cougars here. Nothing like laying your eyes on one to convince you.
It's not surprising the trail cams failed to catch one considering the home range size cougars maintain. Western cougars have been found to have home ranges as small as 10 sq miles and as large as several hundred square miles. One would expect that the more plentiful food sources and less competition in the east would tend to reduce the size of home ranges but the lack of available mates could mitigate that to some extent. In any case, they cover a lot of territory making catching one on a trail cam a very low probability. Seeing one is rare even where the population is much higher than in Indiana. I have a friend who has worked at Crane for about 7 years and though he has not seen one on the base he has talked to several people that have.