A key member of the Sicilian crime family, primarily made up of his brothers, he was best known for his war with the North Side Gang leader, Dean O'Banion.

Genna was suspected of killing Harry Raimondi and Paul Labriola, two Powers supporters that won the elections.

[3][better source needed] On December 18, 1922, Genna was arrested by detectives after being named as a stolen goods fence for a gang accused of killing Joe Lanus.

In 1919, the Gennas obtained a federal license to legally manufacture industrial alcohol, which they sold illegally.

This caused a problem with the North Side Gang leader Dean O'Banion, who went to John "Johnny The Fox" Torrio and Unione Siciliana boss Mike Merlo to get the Gennas to back down.

When Torrio refused, O'Banion began hijacking shipments of alcohol belonging to the Genna brothers.

On November 3, 1924, Dean O'Banion inadvertently signed his own death warrant during an argumentative phone call to arch-rival Angelo Genna.

Their disagreement originated at The Ship, the gambling casino that the North Side gang boss owned along with the Torrio Syndicate.

It was mentioned that Angelo Genna had dropped a large amount of cash, plus a sizable marker.

On May 26, 1925, Moran, Vincent "The Schemer" Drucci, and Hymie Weiss shot and wounded Genna numerous times during a high-speed car chase, causing Genna to crash his car into a lamp post at Hudson and Ogden Avenues.

Capone had sent lilies, Joseph "Diamond Joe" Esposito sent peonies, Torrio sent a huge vase of pink and white carnations.

Included in mass of people were 50 policemen, politicians, lawyers, doctors, and labor union officials.