Born in Brooklyn, New York, in 1899, of an immigrant family, Al Capone quit school after the sixth grade and associated with a notorious street gang, becoming accepted as a member. Johnny Torrio was the street gang leader and among the other members was Lucky Luciano, who would later attain his own notoriety.

About 1920, at Torrio's invitation, Capone joined Torrio in Chicago where he had become an influential lieutenant in the Colosimo mob. The rackets spawned by enactment of the Prohibition Amendment, illegal brewing, distilling and distribution of beer and liquor, were viewed as "growth industries." Torrio, abetted by Al Capone, intended to take full advantage of opportunities. The mobs also developed interests in legitimate businesses, as the cleaning and dyeing field, and cultivated influence with receptive public officials, labor unions and employees' associations.

Torrio soon succeeded to full leadership of the gang with the violent demise of Big Jim Colosimo and Capone gained experience and expertise as his strong right arm.

In 1925, Capone became boss when Torrio, seriously wounded in an assassination attempt, surrendered control and retired to Brooklyn. Capone had built a fearsome reputation in the ruthless gang rivalries of the period, struggling to acquire and retain "racketeering rights" to several areas of Chicago. That reputation grew as rival gangs were eliminated or nullified, and the suburb of Cicero became, in effect, a fiefdom of the Capone mob.

Perhaps the St. Valentine's Day Massacre on February 14, 1929, might be regarded as the culminating violence of the Chicago gang era, as seven members or associates of the "Bugs" Moran mob were machine-gunned against a garage wall by rivals posing as police. The massacre was generally ascribed to the Capone mob, although Al himself was then in Florida.

The investigative jurisdiction of the Bureau of Investigation during the 1920s and early 1930s was more limited than it is now, and the gang warfare and depredations of the period were not within the Bureau's investigative authority.

The Bureau's investigation of Al Capone arose from his reluctance to appear before a Federal Grand Jury on March 12, 1929, in response to a subpoena. On March 11, his lawyers formally filed for postponement of his appearance, submitting a physician's affidavit dated March 5, which attested that Capone, in Miami, had been suffering from bronchial pneumonia, had been confined to bed from January 13 to February 23, and that it would be dangerous to Capone's health to travel to Chicago. His appearance date before the grand jury was re-set for March 20.

On request of the U.S. Attorney's Office, Bureau of Investigation Agents obtained statements to the effect that Capone had attended race tracks in the Miami area, that he had made a plane trip to Bimini and a cruise to Nassau, and that he had been interviewed at the office of the Dade County Solicitor, and that he had appeared in good health on each of those occasions.

Capone appeared before the Federal Grand Jury at Chicago on March 20, 1929, and completed his testimony on March 27. As he left the courtroom, he was arrested by Agents for Contempt of Court, an offense for which the penalty could be one year and a $1,000 fine. He posted $5,000 bond and was released.

On May 17, 1929, Al Capone and his bodyguard were arrested in Philadelphia for carrying concealed deadly weapons. Within 16 hours they had been sentenced to terms of one year each. Capone served his time and was released in nine months for good behavior on March 17, 1930.

On February 28, 1936, Capone was found guilty in Federal Court on the Contempt of Court charge and was sentenced to six months in Cook County Jail. His appeal on that charge was subsequently dismissed.

Meanwhile, the U.S. Treasury Department had been developing evidence on tax evasion charges - in addition to Al Capone, his brother Ralph "Bottles" Capone, Jake "Greasy Thumb" Guzik, Frank Nitti and other mobsters were subjects of tax evasion charges.

On June 16, 1931, Al Capone pled guilty to tax evasion and prohibition charges. He then boasted to the press that he had struck a deal for a two-and-one-half year sentence, but the presiding judge informed him he, the judge, was not bound by any deal. Capone then changed his plea to not guilty.

On October 18, 1931, Capone was convicted after trial, and on November 24, was sentenced to eleven years in Federal prison, fined $50,000 and charged $7,692 for court costs, in addition to $215,000 plus interest due on back taxes. The six-month Contempt of Court sentence was to be served concurrently.

While awaiting the results of appeals, Capone was confined to the Cook County Jail. Upon denial of appeals, he entered the U.S. Penitentiary at Atlanta, serving his sentence there and at Alcatraz.

On November 16, 1939, Al Capone was released after having served seven years, six months and fifteen days, and having paid all fines and back taxes.

Suffering from paresis derived from syphilis, he had deteriorated greatly during his confinement. Immediately on release he entered a Baltimore hospital for brain treatment, and then went on to his Florida home, an estate on Palm Island in Biscayne Bay near Miami, which he had purchased in 1928.

Following his release, he never publicly returned to Chicago. He had become mentally incapable of returning to gangland politics. In 1946, his physician and a Baltimore psychiatrist, after examination, both concluded Al Capone then had the mentality of a 12-year-old child. Capone resided on Palm Island with his wife and immediate family, in a secluded atmosphere, until his death due to a stroke and pneumonia on January 25, 1947.