Abstract: This study proposes the use of finger print as the only biometrical user authentication in a simple ECMA authentication model proposed for a heterogeneous environment in an Online Database Transaction Processing (OLTP) system. An algorithm is proposed in this study which uses finger print scanning as the primary tool for biometrical user authentication and is expected to assure security to high level resources, where there is no much physical security. The study presents the existing authentication models and an analysis is made to justify finger print as the best suitable model among them, for OLTP systems under heterogeneous environment.