Medical Murders - Jim Richards Murder Mysteries, #44

Jim's handyman and night watchman, Fred, is ill and not able to do his work. Jim hires a young girl to help Fred with his job until he gets better. Fred's doctor needs to visit Jim in his office and relates a story of how the doctor feels his patients are being murdered in the hospital. Jim takes the case and brings in Lynn and Deacon to go undercover at the hospital to find the killer. Fred is in a bed next to a man they think may be next to die, so Fred is keeping an eye on the man.
Who is the killer? That's for them to find out. This book is a novella, longer than a short story, but shorter than a novel.