German criminal code allows a preventive detention in case of persistent dangerousness of a perpetrator. Since 2004, this detention can be ordered not only within the criminal conviction but also at the end of imprisonment. Therefore two psychiatric or psychological experts have to assess the further legal risks. For legal aspects, the belated additional preventive detention can only be ordered by the court if there are "new" risk factors which were not known (not in evidence) at the time of the last conviction. The paper reports the results of 17 assessments and the reasons why they were requested (persistent aggressiveness, paedophilia, drug abuse, abortive therapies, schizophrenic disorder, brain damage). In most cases there were no new risk factors. Only in one case the sentence to a belated additional preventive detention became legally valid.