Al Capone was eventually imprisoned for tax evasion. That's all they could use to finish his career. From Wikepedia:
"The federal authorities became intent on jailing Capone and prosecuted him in 1931 for tax evasion. During a highly publicized case, the judge admitted as evidence Capone's admissions of his income and unpaid taxes during prior (and ultimately abortive) negotiations to pay the government taxes he owed. He was convicted and sentenced to 11 years in federal prison. After conviction, he replaced his defense team with experts in tax law, and his grounds for appeal were strengthened by a Supreme Court ruling, but his appeal ultimately failed. Capone showed signs of syphilitic dementia early in his sentence and became increasingly debilitated before being released after eight years of incarceration. On January 25, 1947, Capone died of cardiac arrest after suffering a stroke."