If the cat was indoors at one time, chances are very good that she'll recall those happy times and turn around. The best way to do it is either to cage the cat, or put her in a small bathroom where she can't hide much. Be VERY careful around windows, and screens as a very traumatized cat is likely to smash into the window, or tear open screens to escape. If you can get a good sized cage, cover it with a sheet except for the front door. Place the litterpan, and food up front, and when you have to open the door up, always move slow so not to spook the cat into bolting out. Let her be for several days, and then one good way to test her out is to stuff a garden glove with some cotton, and tie it securely to a stick. Use this to pat her with, and you'll be less apt to lose flesh should she attack you. Never pat their heads at first, start low, and go for the rump, or back first. Hope you can help clean up that awful mess those lousy neighbors left to rot. Good luck!