I had no idea I was buying from a thief at the time I bought it. Shortly after buying, I got tired of the bike so I posted a "for sale" ad on craigslist. The original owner of the bike saw his bike in my ad and he was furious. He contacts me, accusing me of being a thief and threatening to call the police unless I surrender the bike to him immediately. I explain that I bought the bike and that it's mine now. He doesn't care or doesn't believe me. He demands that I bring him the bike for free, otherwise he'll call the cops and have me arrested for petty theft and/or possession of stolen property.
He still has the original receipt for the bike, and the serial number on his receipt matches the number on the bike frame so I know he's the true original owner.
Although I disagree with his hostile attitude, I agree that the bike is really his because when I bought the bike from the thief, that was a fraudulent transaction and true transfer of ownership did not take place.
The true owner of the bike shouldn't have to pay for it twice. Should I give him the bike for free and accept the financial loss? Or should I drag the cops and the law into this? Morally speaking, what is the right thing to do here? Who gets to keep the bike?
The thief who sold me the bike is long gone, he's history, not part of the equation at all.

