Jim Grossman was the man falsely accused of killing his best friend in a case involving a storied vintage car.
Jim's best friend, Cal Hawkins, called him and invited him to his house to see the prize that they'd both been chasing for years: "Little Bastard," the silver convertible Porsche that James Dean owned and died in after a fatal crash. Jim was jealous, but very impressed, and left Cal in the garage to get a camera to capture the first time Cal started it up. As he was getting the camera, he heard a commotion and returned to the garage with the camera rolling and found Cal dead, his head embedded in the windshield.
The Winchesters arrived in Canton to investigate the case and met with Sheriff Rick Carnegie, who immediately informed them that they'd wasted a trip because he already had the man who committed the crime in custody. When they asked who he thought had done it, he showed them the video shot by Jim that captured the moment he discovered Cal's body. The sheriff was sure that it was a cut-and-dried case of a psycho recording his handiwork. Noting the obvious lack in evidence and reasoning, the boys asked to speak to Jim anyway.
Jim told Sam and Dean what he'd already told the local police; he was in the house when the accident happened and didn't even see it. He did, however, hear tires screeching and glass breaking. He told them the car did it, and went on to reveal, to Dean's amazement and delight, that the car involved was "Little Bastard." Dean knew the lore about the trail of death that had followed the car since James Dean died in it. Jim said that he too had of course heard about "the curse," but regarded it as "a load of crap" throughout the years that he and Cal spent searching for it. He said when Cal found it first, he wanted to rub it in his face.
The Winchesters eventually discovered that the car never belonged to James Dean, so no curse was involved, and that the pagan god Leshi was actually responsible for Cal Hopkins' death. The status of the Sheriff Carnegie's case against Jim Grossman was not mentioned again.