If it were me, I would first try to get the guy to buy it back but I wouldnt drive to vegas, I would wait for his buddy to maybe come out. If he doesnt show then driving there would be a waste plus you cant legally drive it to vegas. If he doesnt show I would get the original owner to put in for a new title, as if they lost the title but if you go that route you need to type a document up stating what has happened and as soon as they get the title they are going to transact the car to you, you guys could do it for like a dollar, cause if you ask me they are still the legal owners. It seems to me this other guy (creep) is basically just hearsay from a legal standpoint. Oh and make sure they sign the document you type up, prolly best off to do it in the presence of a notary.
I remember when I bought my first car, well actually it was a ford van, anyway it looked great but it ended up that it was a flood car and had extensive rust throught, but there wasnt much I could do " caviat emptor"