The character you're likely thinking of is "Suitcase" Lou", who appears in the novel "Stone Cold" and its film adaptation. He is a former detective who's trying to stay straight but is pulled back into the life of crime. He is a minor character and plays a role in Jesse's investigation of a murder.
It's possible you're confusing Lou with another character from the books, or that you're thinking of another crime drama altogether. Please let me know if you have any more details about who Lou is and what you are trying to remember.