I know nothing at all about the facts of the murder case this movie is based on. All I know is that in the film, Barbara Graham (Susan Hayward) is portrayed as being completely innocent, having no involvement in the murder other than being present when it happened. I don't know if she was tricked into admitting that fact by an undercover cop pretending to be her friend, either. All I know is that Susan Hayward gives a terrific performance, one that had Oscar™ written all over it (and of course she won one).
Barbara Graham is depicted as a woman who loves a good time, a prostitute who falls in with a couple of bad companions and gets involved in a robbery gone wrong. When the three are arrested, the two men swear that Graham killed the robbery victim so they can get their own sentences reduced. Graham is sentenced to death.
The last part of the movie is set on Death Row as the preparations for Graham's execution go forward, with Graham claiming innocence all the way. Protestations of innocence don't do much for convicted killers, and Graham goes to the gas chamber.
When I saw this movie as a kid, I thought it was great. I didn't know the term "film noir" then, but I'm sure this is one, albeit a late one. Susan Hayward gives a knockout performance, and the rest of the cast isn't bad, either, though most of them are largely forgotten now. There's also a jazzy score that was popular at the time. You can hear some of it in the trailer below. Gotta love those bongos!