It's possible. Sometimes such titles are drawn from actual cases that have been adapted or fictionalized for dramatic effect. There could be elements of truth hidden within the story.
Well, without more context, it's difficult to detail the 'A Killer Among Us' real story. However, generally speaking, such a story might involve a person who blends into a group, like in a small town or a workplace. This individual secretly harbors murderous intentions and starts preying on those around them. It could be a case where the killer is someone no one suspects, like a friendly neighbor or a trusted coworker, and the discovery of their true nature is a shock to everyone involved.
Well, if it is based on a true story, it might be about a real - life killer situation. However, without actually seeing it or having more details about it, we can't really confirm if it is a legitimate piece of work. It could also be a title used to attract attention, and the 'true story' part might be a bit of an exaggeration.