I'm so sorry, Zoom. Take comfort in the fact that you found her (as opposed to her starving to death or worse in that position), with you DH were able to free her, and that they were able to put her down humanely. You did all you could. And yes, some humans suck. Have you thought about putting up posters so her owners (if she had any) might know?

(mom to 3 rescue kitties who she is completely neurotic about keeping in the house)