The HOLMES system requires skilled computer operators with specific investigative skills. Not all law enforcement officers are adept at using computer-based investigative programs, and the purpose of the study was to identify those who possessed computer aptitudes, to follow them through the HOLMES training, and to compare their aptitudes with their achievement in the course. One hundred subjects took the ability tests and the final examination in the HOLMES training course. The computer ability tests measured computer checking, the ability to understand and follow instructions coded in computer language, and a personality test. Step-wise multiple regression analysis was used to estimate the extent to which ability test variables could predict the score on the end of the course examination. Age and qualifications were the best predictors of performance. 4 references.