In order to meet the changing requirements for law enforcement agencies, and to adjust to the applicants’ abilities, the pre-recruitment examination and personnel selection systems of the domestic law enforcement have been placed on new foundations. It became evident that a truly effective new system, which is able to serve both the individual and the organizational effectiveness, can only be developed based on scientific research, and making use of scientific results. As a part of this process, the concept of competencies gained ground, just as in the field of work psychology. Competencies can be defined as personality characteristics, abilities and skills that are essential for effective work achievement. In the Ministry of Interior, the scientific research-based development of the pre-recruitment examination and personnel selection systems started by defining the uniform competencies for leaders of home affairs in 2012 and continued with the development of complex measurement methodology for assessing leader competencies for leaders of home affairs (KVR). During this process, several scientific innovations were applied, what established the development of a new, complete home office competency system, and its integration into the Two-stage Integrated Personnel Selection System. The aim of the present study is reviewing the above-mentioned processes. First, we present the research methodology that established the new, home affairs competency system serving both objectivity and the specifications in law enforcement; and the methodology behind the interactive test systems for
complex measurement of competencies. Later, we review the problems occurring during personnel selection decisions which can be eliminated or reduced by applying neural networks as tools for decision support. Furthermore, we shortly present the basic principles of neural network structures and operations. Finally, we demonstrate how this methodology can be applied in practice in decision support, as it is shown also by a case study.