Female sex-offender research.

This article critically reviewed the research literature on female sex-offenders based on all the identified studies with a sample exceeding 10 from 1989 to 2004. Thirteen studies were identified. Five exploratory studies were individually summarized and critiqued as a group. The eight comparative studies were individually discussed and critiqued. Strengths and weaknesses of the current research were discussed. Conclusions about the research and suggestions for future research were provided. Notable conclusions were: that female sex-offenders are more likely to have been sexually victimized than other populations, offended by themselves, and commit serious forms of sexual abuse. There are also some promising typologies for this heterogeneous population, but they need further replication.

Based on the 13 reviewed studies some distinct features of female sex-offenders emerge as well as areas that need further replication. Sexual abuse victimization has been identified as notably higher in the female sex-offender population by early case reports and prior reviews. The current review supported this finding in a variety of samples ranging from incarcerated offenders to unidentified college perpetrators. There is ample support that female sexual offenders have experienced childhood sexual victimization at a higher frequency than any other groups. Early case reports indicated that female sex-offenders were psychotic. Later studies suggest that psychological problems (excluding psychosis) are common in this population. In particular, substance abuse, depressive, anxiety, dissociation, and post-traumatic stress disorders seem prevalent. In the current review reported a high rate of psychosis and depression, but their findings should be viewed in light of their sample of female sex-offenders referred for a competency to stand trial evaluation, which may have increased the rate of psychosis noted. Conclusions regarding psychological problems including PTSD, depression, and substance abuse are difficult to make based on the current review because the results of the studies investigating psychopathology are inconsistent. Substance abuse was not implicated as a factor in any of the studies, but two mentioned specifically that it was not a factor.

Another important distinction of female sex-offenders, identified by an earlier literature review, is that they often offend with a male co-perpetrator. Out of the 13 studies investigated in the current review only 3 reported that the majority of female sex-offenders had a co-perpetrator; this implies that many do offend alone. The preferred victim's gender still is debated according to two review articles. This is consistent with the findings of the present review indicating that the data are inconclusive as to preferred victim gender, relationship to the victim, and whether female offenders are more likely to deny the crime.

The current critical review revealed some important variables that had not been extensively discussed in prior reviews on this population. Female perpetrators might commit their first offense at an average younger age than other female offenders and that they may be on average younger than male sex-offenders when identified. These findings should be investigated in future studies to determine whether females offend at an earlier age or if they are more likely to be identified at a younger age. It appears that both male and female sex-offenders are more feminine than other adults based on the Bem Sex-Role Inventory and this needs further investigation. The current review suggests that female sex-offenders did engage in serious forms of sexual abuse (penetration) as reported in three studies. However, Allen reported the contrary. In summary, there is a clear agreement among the investigated studies that the female sexual-perpetrator population is very heterogeneous and should be treated as such.

Future research should include a clear definition of sexual abuse/offense because it is an integral part of this type of research. Without a definition of what types of offenses were included (e.g., fondling, penetration) contribution to the literature will be diminished because comparisons across samples will be problematic. It is evident from the critical review that there is a lack of standardized measures (with adequate psychometric properties) utilized in this research literature. Incorporating better measures would, therefore, make a substantial contribution to the knowledge base of female sex-offenders. In particular, personality measures are needed to replicate earlier findings regarding the prevalence of psychiatric disorders among female sex-offenders. Most of the samples investigated were Caucasian and future literature should attempt to increase the number of minority participants.

A very important area of future work is to replicate, refine and combine typologies instead of establishing new names for already identified categories. Mathews et al.'s typology is the most frequently cited, but it was not based on any statistical analyses and some of their proposed categories had a sample size of one. Vandiver and Kercher used statistical analyses and a large sample for their proposed typology. They partially validated the Mathews et al. typology but indicated that a two-category extension might be warranted. This combination typology might be useful to categorize the diverse female sex-offender population, but it is still just a starting point and needs further validation through controlled studies. Further development of typologies and cognitive distortion measures, frequently cited in the male sex-offender literature, would be valuable to individualize treatment.

Although there is much support for childhood sexual victimization in the female sex-offender population, future studies should attempt to get collateral evidence for the victimization considering there might be a secondary gain for female perpetrators to report victimization (e.g., sympathy, lesser sentences, and compassionate treatment). Lastly, a lack of information concerning the treatment and potential recidivism of the female perpetrators is evident. Some authors suggested that female perpetrators should be treated differently from the male perpetrators and that they will have more successful outcomes in a nurturing and supportive environment. than the often confrontive environment of male sex-offender treatment. This differential treatment suggestion still needs to be scientifically studied and evaluated. Overall, the scientific bar needs to be raised for future studies in this area to produce more scientifically sound research that will enable us better to support the conclusions made about this population.