In the context of criminal forensic evaluations, experts are often confronted with the problem of offenders' claims of crime-related amnesia. Because of the far-reaching legal consequences of the expert opinion, the nature of the suspected memory disorder has to be investigated with special care and due consideration of differential diagnoses. While the diagnosis of organic amnesia is comparatively easy to make, the same is not true for dissociative amnesia. Despite existing theoretical explanations such as stress, peritraumatic dissociation or repression, to date there is no sound, scientifically based and empirically supported explanation for the occurrence of genuine, non-organic crime-related amnesia. In the criminal context of claimed amnesia, secondary gain is usually obvious; thus, possible malingering of memory loss has to be carefully investigated by the forensic expert. To test this hypothesis, the expert has to resort to methods based on a high methodological level. The diagnosis of dissociative amnesia cannot be made by mere exclusion of evidence for organic amnesia; instead, malingering has to be ruled out on an explicit basis.