When an eyewitness suffers an impairment of memory for a perpetrator because the criminal used a weapon during the crime, this impairment is called the weapon focus effect. The literature is split on how this arises: Some implicate the narrowing of attentional cues to the weapon because the arousal of the victim increases, whereas others claim that the weapon is a novel object in most everyday contexts, and novel objects demand more attention than contextually appropriate ones. The current study employed a simulated crime paradigm featuring a normal, novel, or threatening object. Timing of the object's presentation was manipulated such that it was visible before, after, or during the time when the culprit's face was visible. Target-present and target-absent line-ups as well as retrospective questions were administered. Both the novel object and the weapon resulted in increased mistaken identifications in target-absent line-ups. Structural equation modeling suggested that object novelty mediated this effect. Copyright © 2014 John Wiley & Sons, Ltd.