At this point you may be more interested in putting this nightmare behind you, but have you considered hiring a private detective? It's not as expensive as you might think - and though it wouldn't guarantee results it's probably a better bet than a reward. Look in the Yellow pages (usually under 'investigators') - there should be a listing. A lot of times they're retired cops and pretty dedicated guys. Especially if you feel you know the general area, a private eye could stake it out. I know, it sounds like something from a bad movie, but these people really exist and do good work. I have a good PD friend in Cleveland (who also happens to be a big-time dog person) - he might be able to recommend somebody down in Cincinnati (or make some other good suggestions) if you're interested.
I can't imagine what this must have been like for you. There are bad people out there.