Pan and Wollack (2021) proposed an algorithm for detecting compromised items. The present study extends their algorithm to an approach detecting both examinees with item preknowledge and compromised items simultaneously. The development contains two parts: (1) instead of one-time detecting, this approach draws on ideas in ensemble learning, conducting multiple detections using subsets of data; (2) instead of identifying suspicious elements based exclusively on item-level aberrance, this approach considers both item-level and examinee-level aberrance. Results show that under the conditions studied, provided the amount of preknowledge is not extreme, the proposed ensemble-unsupervised-learning-based approach controls the false negative rates at a relatively low level and the false positive rates at an extremely low level.