During the course of a criminal investigation witness vetting, a detective's process of determining the credibility and weight of witness information, can lead to errors in an investigation that can go virtually unchallenged. Witness confidence, opportunity to view, and type of information proffered were examined in relation to detective inferences about witness reliability, accuracy, and probable cause to arrest. Experiment 1 involved 39 sworn law enforcement officers, and experiment 2 involved 43 sworn law enforcement officers and 86 mock detectives. Participants viewed a digital recording depicting a witness describing a gas station robbery (Experiment 1) or a campus mugging (Experiment 2). Witness confidence and detectives' inferences about culprit information influenced the vetting process and lent credibility to a confident witness whose accuracy was objectively unknown. Furthermore, the evidence indicates that sworn law enforcement are comparable with untrained observers in their use of social inference cues (i.e. confidence) in determining witness credibility; however, social inference can be assuaged by the rational, rule‐governed, decision framework established for witness vetting. Social inference processes inherent in the detective‐witness dyad is influenced by legal procedures in vetting witness information. Copyright © 2013 John Wiley & Sons, Ltd.