In information gathering interviews, follow-up questions are asked to clarify and extend initial witness accounts. Across two experiments, we examined the efficacy of open-ended questions following an account about a multi-perpetrator event. In Experiment 1, 50 mock-witnesses used the timeline technique or a free recall format to provide an initial account. Although follow-up questions elicited new information (18-22% of the total output) across conditions, the response accuracy (60%) was significantly lower than that of the initial account (83%). In Experiment 2 (N = 60), half of the participants received pre-questioning instructions to monitor accuracy when responding to follow-up questions. New information was reported (21-22% of the total output) across conditions, but despite using pre-questioning instructions, response accuracy (75%) was again lower than the spontaneously reported information (87.5%). Follow-up open-ended questions prompt additional reporting; however, practitioners should be cautious to corroborate the accuracy of new reported details.