Al Capone jailed for first time in Philadelphia's Eastern State Penitentiary for carrying concealed deadly weapons

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.

In 1929, Bureau of Prohibition agent Eliot Ness began a successful investigation of Capone and his business. Shutting down many breweries and speakeasies Capone owned, Ness brought down his empire slowly. To lie low, Capone arranged to have himself jailed in a comfortable cell at Philadelphia's Eastern State Penitentiary for nine months beginning August 1929. Upon his return to Chicago, he quickly found himself in the legal quagmire that effectively removed him from power.

The Federal 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.