Dan, the eastern cougar has been thought to be extinct for a long, long time.
Cougar behavior is pretty well documented as to migration, territorial areas and loyalty to those territories and such. Of course, some migration takes place in search of food or because of disputes. I’m not well enough versed, without my books handy to do a synopsis on it, but suffice to say, “hard evidence” of “wild” cougars is the determining factor for saying they do exist in a particular area.

The thing that many folks are misinformed about is the thought that cougars are these ghosts of the forests and somehow leave no sign when in fact they leave copious amounts of identification sign. Cougar kills are very identifiable as are tracks, scat, scratching trees, den sites and paw prints.
Also, in South Dakota, 7 road-kill cougars were picked up in the Black Hills in a period of 3 months. The entire population of the Black Hills is estimated to only be around 200 cougars. So, the idea that they never show themselves and are so elusive that they cannot be documented to exist, just is not truth.

Yes, pets have been released and recaptured or killed. All cases that I know of to date have been domestic releases.

The ignorance is in accepting something without reasonable evidence to make it acceptable.

I haven’t seen anyone on here say – they absolutely do not exist. Most of us react to sensationalism that is borne out of emotion and sometimes someone just wanting attention for having “sighted” something rare and special.