Joe Halderman, who is accused of attempting to extort $2 million out of David Letterman, ate lunch with a veteran Nashville homicide detective just days before he left a note demanding $2 million in Letterman's car.

Sgt. Pat Postiglione, who heads the Nashville police department's cold case unit, told Gawker that he had lunch with Halderman in Nashville in the last week of August, when Halderman was traveling there to speak to a meeting of the National Information Officers Association.

"He seemed OK," said Postiglione, who worked for years with Halderman on a 48 Hours story Halderman produced about the 1996 murder of Nashville socialite Janet March. Postiglione's cold case unit solved the case in 2004, and he featured prominently in Halderman's piece. "He seemed like he had lost quite a bit of weight, but other than that he was normal. We talked about different cases, and he said he wanted to come back and do a story on a cold case."

Little did Postiglione know that on September 9, a little over one week after that lunch, Halderman would hatch his alleged extortion plot by handing a blackmail note to Letterman's limousine driver outside his Manhattan home.

Postiglione said Halderman's work on the March story, which took him to Nashville several times over several years, made him a lot of friends in the Nashville police department. "We knew him fairly well," he said. "We were stunned. He's much smarter than that, and he was clearly pro-police to the max." Halderman's true-crime stories for 48 Hours put him in close touch with a lot of law enforcement officers, and made it his job to tell stories of how the bad guys got caught by the cops—which makes his apparently ham-fisted attempt in Letterman's case all the more mystifying. "If he was going to do something like this," Postiglione said, "you'd figure he would have come up with something more sophisticated. He tried to cash a $2 million check and didn't think anyone would notice?"