The horrific nature of murder using different types of weapons has been an important focal point ofmany criminological studies. Weapons that are used in murders seem to play dominant roles in murderinvestigations as they may provide information leading to arrest. The established factors for weaponusage include environmental context, demography and availability of weapons. However, there isinsufficient research attention on the psychological functioning of murderers for particular weaponusage. In light of this, the current study seeks to narrow this gap of information by identifying theinfluences of psychological traits on weapon usage among a sample of male murderers. The presentcross-sectional study was conducted among 71 male murderers incarcerated in 11 prisons withinPeninsular Malaysia. The selection of the sample was based on predetermined selection criteriausing a purposive sampling method. A guided self-administered questionnaire comprising sociodemographyvariables and four Malay validated psychometric instruments: Zuckerman-KuhlmanPersonality Questionnaire-40-Cross-Culture, Self-control Scale, “How I Think” Questionnaire andAggression Questionnaire; was used. Independent sample t-test was performed to establish themean score differences of psychological traits between the murderers who used single and multipleweapons while Kruskal-Wallis tests were carried out to ascertain the differences between the specifictypes of weapons used among the murderers. Following this, one-way ANOVA was carried out toascertain the psychological trait differences among the murderers according to the different sourcesof weapon. Results indicated specific psychological traits influenced the number(s), source(s) andtype(s) of weapon used in committing murder. The findings have implications for the psychologicalprofiling of unknown murderers within the Malaysian context.