An illicit international trade of environmentally sensitive commodities has become a growing concern for customs organizations in developing countries, which are poorly informed about exotic wildlife items and transnationally organized trade networks in various parts of the world. These organizations are expected to have sufficient capacity and knowledge for detecting and preventing environmental crimes at the border. Past studies have not paid substantial attention to how governmental organizations' internal factors, such as organizational culture, can contribute to enhancing their environmental crime law enforcement. Therefore, this research aims to examine the extent to which organizational culture at Mongolian customs organizations affects human resource capacity in regulating environmental crimes. In doing so, we conducted an online questionnaire survey among 441 Mongolian customs officers. The results show that the customs officials' knowledge about environmental crimes largely focused on wildlife trafficking. Their knowledge about persistent organic pollutants and hazardous materials appeared to be limited. Leadership styles did not appear to reward employees' environmental crime detection. Our correlation analysis identified that young female customs officers with limited work experience tend not to be confident in detecting crimes. This problem can be alleviated through information exchange among colleagues and additional training, but it did not seem to be the case among the respondents as they tend to rely more on other relevant government agencies for additional information than learning from their colleagues. Our regression analysis identified that under motivated leadership, the respondents with strong work commitments tend to be more knowledgeable and capable about CITES crime detection. They also demonstrated a high level of interests in environmental protection matters at large. Generally, the customs officers' capacity to detect environmental crimes tended to be based on personal experience. The institutionalized support for enhancing work performance capacity, therefore, was limited.