From the beginning, the tale seemed to skirt the edges of the possible — a mountain lion reported to be stalking the wilds of Greenwich, Conn., seen near fancy private schools and busy roadways. But the sightings were confirmed in early June by paw prints, photographs and animal droppings, and then, more dramatically, by the lean body of a 140-pound male creature killed by a sport utility vehicle on the Wilbur Cross Parkway in Milford on June 11.