Abstract: The conventional approach for criminal investigation and trial of cases in the law courts in developing countries like Nigeria is usually slow and unreliable. Consequently, the society is characterized by prolonged periods of detention of the suspects awaiting trial and congestion in the prisons and law courts. This paper attempts to describe the application of Artificial Intelligence (AI) in the investigation of ATM fraud in Nigeria. An Expert System (ES) is proposed which provides and supports the storage and intelligent interactive processing of the knowledge acquired by and experience of the human expert in the domain of criminal investigation, law and justice. One of the objectives of the study is to provide an intelligent computer-based system which will smooth, enhance and speed the efficient and reliable performance of the human expert in the domain of criminal investigation of ATM fraud in Nigeria. Other objective is to provide a system for computer aided learning of criminal investigation.