This document proposes a new one-to-many data linkage technique using a One-Class Clustering Tree (OCCT) to link records from different datasets. The technique constructs a decision tree where internal nodes represent attributes from the first dataset and leaves represent attributes from the second dataset that match. It uses maximum likelihood estimation for splitting criteria and pre-pruning to reduce complexity. The method is applied to the database misuse domain to identify common and malicious users by analyzing access request contexts and accessible data. Evaluation shows the technique achieves better precision and recall than existing methods.