The man administering the polygraph test to convict Richard Conte was the inventor of the polygraph or lie detector machine, Leonarde Keeler. He played himself in the movie.
James P. McGuire served as a Technical Advisor on this film. Jack McPhaul was the Chicago Times reporter who wrote the articles on which this film is based. The character played by James Stewart is a composite of McGuire, who was the legman, and McPhaul.
In 1946, James McGuire and Karin Walsh, the real-life people on whom James Stewart's and Lee J. Cobb' characters, respectively, were based, won the prestigious Heywood Broun Award for excellence in investigative journalism for the Chicago Times for "stories helping free a man wrongly convicted of murder."
The "roundhouse" where Frank Wiecek (Richard Conte) is kept at the Stateville prison was the only remaining panopticon still in use in the United States in the 1990s. It was closed in 2016, but the structure remains, due to its historical significance.
When McNeal tries to convince Zaleska to take the blame for the murder to exonerate Wiecek, Zaleska asks if he should name "Joe Doakes" as his partner. At the time, Joe Doakes was another name for "Joe Blow" or "John Doe".