I'm sorry, without having read 'The Ruth Finley Story', I can't accurately say who the killer is. But killers in stories are often complex characters. They might seem normal at first but then be driven to murder by internal or external factors. In some stories, the killer could be a character who is close to Ruth Finley, like a friend or a family member, and something happens that causes them to snap. It could be a betrayal, a misunderstanding, or a long - held grudge that finally erupts into violence.
Since I don't know the exact details of 'The Ruth Finley Story', it's difficult to name the killer. However, in many stories, the killer often has a motive such as greed, revenge, or power. Maybe in this story, there is a character who wants to take something from Ruth Finley, be it her position, her wealth, or something else, and that could lead them to commit a killing. It could also be related to some dark secrets from the past that are gradually uncovered as the story progresses.
I'm not sure specifically who the 'killer' is in 'The Ruth Finley Story' as I don't have detailed information about this particular story. It could be a character that is revealed through a series of events in the narrative, like a jealous rival, a person with a hidden agenda, or someone involved in a mystery that unfolds.