Little consensus exists regarding how the details of truthful and false allegations of traumatic victimisation may change over short and long time intervals, yet this cue is utilised in the assessment of witness, victim and suspect credibility. The present study involved a narrative analysis of the details written within 147 sets of allegation statements across both short‐term (~3 months) and long‐term (~6 months) intervals. Overall results indicated that true allegations contained more consistent details, omissions and commissions, although the rates of change over time were variable. These changes appear to result from natural variations in memory and recall over time. However, direct contradictions (inconsistent details) were more prevalent in false allegations, and these claims were more stable over time, suggesting ‘script‐like’ processing. These results have implications for our understanding of testimonial alterations and how determinations of veracity are influenced by statement details. Copyright © 2014 John Wiley & Sons, Ltd.