John saw an ad on Craigs List for a used sit upon tractor mower. He contacted Cheryl who was selling it. He tried it out and was happy with it. He gave her the $400 she was asking for it. Cheryl typed out a Bill of Sale and signed it. Three days later the police arrived at Johns door. They told him the mower had been stolen, and he would have to return it to the rightful owner. Discuss Johns legal situation concerning ownership.