In the past several years, there has been an explosive growth of amount and diversity of electronic information available over the computer networks. Related information is often distributed among heterogeneous resources. While the users of the computer-based information networks have access to more data resources, they are facing certain problems with integrating data from multiple resources. A mediator-based information system addresses these problems and provides users and applications a uniform access to heterogeneous distributed data resources. Upon users request, such a system retrieves data from available and relevant resources dynamically, integrates these date by resolving various heterogeneities, and brings them to a proper abstraction level for analysis or decision making. Several mediator-based information systems have been developed by different research groups. Among them, InfoSleuth developed at MCC, combines the mediator technology with other advanced technologies such as software agents and ontologies, and performs information gathering and analysis on behalf of its users. InfoSleuth uses resource agents to represent data resources and retrieve data from these resources based on their content. Different resource agents have been implemented in InfoSleuth to access relational databases, text repositories, image collections, etc. This work discusses the InfoSleuth system and its resource agents. It also presents the development of a new type of resource agent, which incorporates an object-oriented database into InfoSleuth and accesses information stored in the database. The particular object-oriented database system used by this resource agent is ObjectStore PSE Pro.