The paper explores the misuse of information systems for corrupt practices in the Nigerian public sector as a phenomenon under study. Routine Activity theory, Model of Emergent IT Use, and Normalization theory were used as lenses. Danermark et al.’s six stage framework with a single case-study was adopted as the critical realist methodology. The anti-corruption and regulatory agency, the Economic and Financial Crimes Commission of Nigeria, is the case in focus. Semi-structured interviews, archival documents and press media were used as data sources. By analyzing the data, we identified motivated offender, suitable target, and the absence of a capable guardian as the entities/factors that characterized the phenomenon. Political clientelism patronage, socialization, embeddedness of corrupt routine into IT artifacts and rationalization were identified as causal mechanisms with culture as the enabling conditions. Dysfunctional structures of the Nigerian public sector were also identified as structures that breed the mechanisms. The study findings contribute to theory, practice, and the methodology of critical realism.