Steve,
Don't bust my stones. I am not one to make rumor. It was all over the news in Pittsburgh for weeks. Alot of people either saw it or saw tracks near their houses. Hard to find the reports now as most links are now broken. But, take my word, it happened.
Here is one.
http://www.thepittsburghchannel.com/video/2860471/detail.html
The GC came out and basically shrugged their shoulders and left.
What were they gonna say?
The thing moved on eventually.
The proof you demand is tough to get. But, it will happen.
Cougars are hard to find even where there are good populations.
Imagine trying to pin down a handfull in this big state.