The Microscope Mystery(1916)

When a wealthy hypochondriac is dissatisfied by the care of the town doctor (Doc Arnold), he consults with a new physician in town who swindles him out of a large sum of money. When his daughter tries to retrieve the check, the quack (Dr. Bell) turns up dead with a gun shot wound to the chest. Doc Arnold lends his expertise to the investigation and solves the case by finding microscopic evidence on the murder weapon left at the scene.