Jimmy is the good guy. He is the viewpoint character. He is the guy we are rooting for--especially after he falls in love and becomes a changed man. We want to see him go straight, to become an honest businessman, an asset society, a good husband and father. Ben Price is a tough cop. He is a minor character. We don't identify with him, although we can understand him and his point of view. He shows his hard-boiled nature when he is heard to say:

“I can see that Jim Valentine has been here. He is in business again. Look at the way he opened this one. Everything easy, everything clean. He is the only man who has the tools to do it. And he is the only man who knows how to use tools like this. Yes, I want Mr. Valentine. Next time he goes to prison, he’s going to stay there until his time is finished.” 

The reader is emotionally moved when the little girl gets locked in the bank vault and Jimmy makes a truly noble sacrifice to save her life. He opens the suitcase containing the tools Ben Price refers to in the above quote. These are damning evidence against him. They can be used to prove he committed the three safecracking jobs in Richmond, Logansport, and Jefferson City shortly after being released from prison. He will lose everything he has gained since he came to Elmore, including the girl he loves. We don't want to see him lose everything he has achieved through his reformation, so we are gratified when we realize that the tough cop Ben Price has been moved in exactly the same way that we have. Ben Price is only temporarily a good guy. He may let Jimmy Valentine go, but he will continue tracking down crooks and sending them to prison, because that is who he is and what he does.