The film parallels the true story of a Chicago newspaper reporter who proved that a man jailed for murder 11 years previously was wrongly convicted.

Wiecek is based on Joseph Majczek, who was wrongly convicted of the murder of a Chicago policeman in 1932, one of the worst years of organized crime during Prohibition.

Eleven years later, Wiecek's mother puts a classified ad in the Chicago Times offering a $5,000 reward for information about the true killers of the police officer.

[citation needed] Fox had obtained the necessary legal clearances from the persons involved in the story and had dispatched producer Otto Lang and writer Leonard Hoffman to gather material for the film in Chicago.

Aside from Chicago, locations for Call Northside 777 included Santa Monica and also the Illinois Stateville Prison "Roundhouse" annex,[2][3] which was closed in 2016 but briefly reopened in 2020 for COVID-19 housing.

Among them was that Wiecek’s innocence was determined not by enlarging a newspaper headline to catch a key witness lying about a minor point, but that the prosecution had suppressed the fact she had initially declared that she could not identify the two men involved in the police shooting.

"[8] The website DVD Verdict made the case in 2006 that the lead actor may be the best reason to see the film: "Its value exists mainly in Stewart's finely drawn characterization of a cynical man with a nagging conscience.