Al Capone, the boss of organised crime in Chicago, was convicted on October 17, 1931, of evading federal income tax, and he was sentenced to eleven years. It was not the crime the public wanted him to go down for. He had ordered murders, run the bootlegging trade and corrupted the city, and none of it could be made to stick in court, because the witnesses died or vanished, and the records were clean. The tax charge was what the government had left.
He was not meant to be the target. Capone had built an empire on the illegal liquor of Prohibition, and he ran it from a suite in the Lexington Hotel, and the money poured in faster than it could be hidden. The government had no way to prove the murders, but it could prove that he had spent and lived on income he had never declared, and the agents who built the case, led by the accountant Frank Wilson, worked from the receipts and the ledgers that the gang itself had kept.
The trial was quick. The defence was weak. Capone's lawyers tried to bargain, and he arrived expecting a deal, and the judge threw the deal out and sent the case to a jury, which convicted him in short order. He appealed, and lost, and he entered prison in 1932, first at Atlanta and then at Alcatraz, and the years inside, and the syphilis that had been eating at him, left him a diminished man.
He never regained power. It was gone. He was released in 1939 and lived out his life in Florida, sick and mostly forgotten, and he died in 1947. The conviction on a tax charge, of a man who had seemed above the law, is the example the country still uses for the principle that the one charge a criminal cannot escape is the money.