Predicting the likelihood of future sexual recidivism: Pilot study findings from a California sex offender risk project and cross-validation of the static-99

Pilot findings on 137 California sex offenders followed up over 10 years after release from custody (excluding cases in which legal jurisdiction expired) are presented. The sexual recidivism rate, very likely inflated by sample selection, was 31 percent at five years and 40 percent at 10 years. Cumulatively, markers of sexual deviance (multiple victim types) and criminality (prior parole violations and prison terms) led to improved prediction of sexual recidivism (receiver operating characteristic [ROC] = .71, r = .46) than singly (multiple victim types: ROC = .60, r = .31; prior parole violations and prison terms: ROC = .66, r = .37). Long-term Static-99 statistical predictive accuracy for sexual recidivism was lower in our sample (ROC = .62, r = .24) than the values presented in the developmental norms. Sexual recidivism rates were higher in our study for Static-99 scores of 2 and 3 than in the developmental sample, and lower for scores of 4 and 6. Given failures to replicate developmental norms, the Static-99 method of ranking sexual recidivism risk warrants caution when applied to individual offenders.