The present study investigated how alibi witnesses react in the face of an innocent suspect’s confession. Under the pretext of a problem-solving study, a participant and confederate completed a series of tasks in the same testing room. The confederate was subsequently accused of stealing money from an adjacent office during the study session. After initially corroborating the innocent confederate’s alibi that she never left the testing room, only 45% of participants maintained their support of that alibi once informed that the confederate had confessed (vs. 95% when participants believed the confederate had denied involvement). Even fewer (20%) maintained their corroboration when the experimenter insinuated that their support of the alibi might imply their complicity. The presence of a confession also decreased participants’ confidence in the accuracy of the alibi and their belief in the confederate’s innocence. These findings suggest that a police-induced confession can strip an innocent confessor of a vital source of exculpatory evidence. This effect may well explain the often-puzzling absence of exculpatory evidence in many cases involving wrongful conviction.