Max Planck Institute for Foreign and International Criminal Law

Some central results for rape and indecent assault (hereafter mentioned only as rape) are presented here:

It turned out that the age dependent frequency of rape is nearly constant, after a strong increase during early puberty. This could be witnessed for the age range starting at about 17 years up to an age of 30 years (as demonstrated by the rates shown in the figure). This is a noticeable result, because in general the age of dependency of delinquent behaviour shows a roll-back effect after a maximum peak during late adolescence. It should be considered, however, that this result is based on longitudinal data, meaning that the effects of individual ageing may also be influenced by possible societal changes. Actually, it seems as if the nearly constant shape with age in the case of rape is a result of an increase in the reporting of cases of rape that occur in the family or in other close relationships. In particular, during the 1990s there was a marked increase in the number of reported rape cases where the offender and the victim had a close relationship, while the number of cases in which the victim did not know the offender remained constant.

A great advantage of the Freiburg Cohort Study is that the persons in principle are followed over their life course. So it is possible, even for cases involving rape, to distinguish between a first offence and any subsequent following offences. It turns out that nearly every case of rape is a first time registration (over 80%, see the rate of first time occurrences of rape in the figure in comparison to all registrations of rape). This implies both that nearly all people registered for rape have no specific history in this area of delinquency, and, as follows, recidivism has a low rate of occurring in the case of sexual violence. From the data of the Freiburg Cohort Study the estimate for recidivism is below 20% over the following 10 years.

Over the course of life up to age 30, about 0.4% of German males are registered at least (and mostly only) once for rape (see the cumulated rates in the figure). The group size of registered rape offenders increased in a nearly linear fashion with age. This corresponds to the constant (flat) age dependency of the (first time) registration rates mentioned above. Moreover, this is in contrast to the typical age dependency of delinquency, which is also shown in the figures (general delinquency). As also mentioned above, this is probably caused by an increase of reports being made.

If the aforementioned facts would lead to the impression that rape is mostly a singular event, this is only true for this specific kind of delinquency, and not for other delinquent acts of these sexual offenders. In general, throughout the life course of sexual offenders there are other delinquent acts before or after the case of rape. From all the German males which were registered (mostly once) for rape occurring before and up to age 27, about 16% could be said to be life course persistent offenders. On the other hand, a group of about 14% had no additional registrations at all. The majority of these sexual offenders (70%) fall between these extremes.

Furthermore, it could be demonstrated that the data registered by the police or the courts would not be sufficient for prognostic purposes. This remains true even if the different kind of delinquent acts are taken into account separately. The best estimate of a multivariate analysis had been an explanation of about 8% of the variance (R² = 0.08).