This is kind of an out-there theory, but to bolster your prostitute point, she had a black eye in the postmortem. I took another look, and while it's just as likely that it's random pooling from however the body was sitting, or from being tossed down the shaft, it's also possible she got into an altercation before she was shot while fleeing. Sorta wish they would give more details on how she was shot, and where, since that can help determine the possible way in which she was (it'd be pretty hard to get a clear shot clean in the back of the skull if it wasn't execution-style, for example). But then, that might also be semi-useless info.
If this was more recent, I'd say we should suggest to LE to cross-reference her picture with known prostitutes in the Vegas area. But it was a long time ago, those records might not exist anymore. :\