James Traficant, the flamboyant former Democratic congressman from Ohio who recently completed a seven-year stint in jail for bribery and racketeering, has announced that he plans to run for Congress this year as an independent. As I detail in my new book, “The Devil and Sherlock Holmes: Tales of Murder, Madness, and Obsession,” Traficant’s history is much more sordid and disturbing than many realize, in ways that extend well beyond his conviction in 2002.

Traficant emerged out of perhaps the last truly mobbed-up county in America, a place in Ohio’s Mahoning Valley where people were often murdered or disappeared, and where, until an F.B.I. sting in the nineteen-nineties, the Mafia controlled virtually every aspect of society. In 1982, even before Traficant began his congressional career, he was indicted for allegedly taking more than a hundred thousand dollars in bribes during his campaign for county sheriff. In an old box in a courthouse, I found a transcript of a tape recording in which Traficant was caught seemingly scheming with the Carabbia brothers, reputed leaders of the Mob known as Orlie the Crab and Charlie the Crab. (Charlie later disappeared without a trace.) According to the transcript, Traficant acknowledged receiving bribes, and indicated that, in return, he would use the sheriff’s office to protect the Mafia’s rackets. Charlie told Traficant, “Your uncle Tony was my goombah … and we feel that you’re like a brother to us.” Traficant assured his benefactors that he was a “loyal fucker,” and if any of his sheriff’s deputies betrayed them “they’ll fuckin’ come up swimming in [the] Mahoning River.”

At trial, Traficant claimed, as he vowed on the tapes he would if he were ever caught, that he was simply trying to infiltrate the Mafia. “I got inside of the Mob,” he insisted, adding, “I fucked the Mob.” Astonishingly, he was acquitted; but during a subsequent civil trial in which he invoked the Fifth Amendment, he was found liable by the I.R.S. for taking bribes and for evading taxes. None of this made him a pariah in Mahoning County. Instead, he become a local hero—the man who defied the Feds—and went on to be elected overwhelmingly to nine terms in Congress. He won in 2000 even though it was clear that he was facing a new indictment and even though his longtime congressional chief of staff admitted that he had been a “bagman” for the Mafia. In 2002, Traficant was finally convicted of bribery, racketeering, tax evasion, and obstruction of justice. At his sentencing, the judge called him “full of deceit and corruption and greed.”

How Traficant fares in the upcoming election will be a sign of whether the Mahoning Valley has finally purged its past.