Thin slice studies are studies that examine judgments based on brief exposure to expressive behaviours or still images. One previous study has examined the prediction of outcomes within a law enforcement context from thin slices of a police-public encounter (Suss & Ward, 2012). The present study extends this research by examining how variables - including operational years of experience, training, familiarity with the encounter, confidence in the prediction, and thin slice length - impact prediction accuracy. Participants were asked to predict whether the subject would harm/attempt to harm the officer(s) after each video they viewed. My results demonstrated that more training, greater familiarity, and greater confidence in one's predictions was associated with greater odds of providing an accurate response. Most of these variables' relationships with accuracy disappeared when examining longer thin slices. Finally, specialized police training, years of experience, and familiarity were found to predict greater confidence in one's predictions.