ABSTRACT In a criminal investigation, displaying an unexpected emotional demeanor could trigger suspicion or perceptions of involvement. Across two studies, mock investigators read a case summary of a preliminary investigation where emotional demeanor (expected/unexpected) and gender of a person of interest (POI) in the investigation (man/woman) were systematically varied. In the second study, a cognitive busyness manipulation was included. In Study 1 (n = 420), an unexpected emotional demeanor led to lower ratings of appropriateness, negative affect display, credibility, and inflated perceptions of suspicion. These results were replicated in Study 2. In Study 2 (n = 396), results showed both main and interaction effects for both emotional demeanor and gender on judgments of several relevant evaluations including suspicion, involvement, and credibility, evidencing the influence of emotional demeanor at a very early stage of investigation, particularly for females. Cognitive busyness did not affect any evaluations of the case or POI.