In this paper we present the concepts and implementation of a data space system for the management of data from heterogeneous sources in the criminal justice field. Our system exploits domain knowledge in the field of justice to streamline and to relate the content of different databases in the chain. In our system, domain knowledge is encoded in a space manager layer. Furthermore, in this layer it is decided which databases should be used to answer a query. This decision is taken on the basis of the encoded domain knowledge, and the content of the databases and its quality.