I have not read all the suggestions yet but get a box trap (Have a heart) and set it uo close to the house thinking about how she would slink near some shrubs or near the edge of a porch. use stinky food as many suggested and put a towel or dark cloth over it that smells like home. Hope fully S she will think it is her "home cave" and the human smells will keep you from catching as many varments. I have raised Bengal cats for years. Some of my escapees were very shy. One I had given up on and I think it was 2 or 3 weeks and she was caught.
Robin