The prosecution of sexual assault cases: correlation with forensic evidence

We sought to determine the association between historical and physical evidence with judicial outcome in sexual assault cases.

A population-based, retrospective review of forensic evidence was conducted for all sexual assault cases reported in Duval County, FL, during a 2-year period. Variables examined included age, race of victim, evidence of trauma (body, genital, or both), presence of spermatozoa at the time of the forensic examination, weapon use, and whether the victim knew the assailant. In cases in which an arrest was made, logistic regression was used to estimate the strength of association with the outcome of conviction in sexual assault cases.

During the study period, 821 sexual assaults were reported, and 801 forensic examinations were performed. The victims were predominantly female (776; 97%), with 409 (51%) being black, 376 (47%) white, and 16 (2%) other minorities. A suspect was identified in 355 (44%) of the 801 cases for which a sexual assault forensic examination was conducted. No suspect was identified in 446 (56%) of these cases. There were 271 arrests made. The police did not have enough evidence to arrest a suspect after detention in 84 cases. For those cases in which a suspect was arrested, 153 had charges dropped, 89 were found guilty, 2 were found not guilty, and 27 cases were still pending or the files were sealed and unavailable for review. There was evidence of trauma in 202 (57%) of the examinations, and spermatozoa were found at the time of the forensic examination in 110 (31%) of the cases in which a suspect was identified. Logistic regression found that victims aged younger than 18 years, the presence of trauma, and the use of a weapon by the assailant were significantly associated with successful prosecution. There was a trend toward conviction if the victim was white.

Emergency physicians have an obligation to provide care for victims of sexual assault cases. This care includes a possible legal defense. To that end, emergency physicians should be vigilant in the documentation of the history of the event (eg, weapon use) and in the documentation of traumatic injuries because these factors can assist in a successful prosecution.