RESUMO
This article presents a systematic review of the available literature on 'what works' in cold case investigations, with a specific focus on psychological evidence-based research. Long-term unsolved and cold cases present their own unique set of challenges, such as lack of hard evidence, recall accuracy, and witness credibility. Therefore, this review provides a collated base of research regarding preventative methods and investigative tools and techniques developed to highlight gaps in the literature and inform best practice in cold case investigations. The review features victim and crime characteristics that may contribute to a case becoming cold and displays contributing factors to cold case clearance. Although promising, at present, psychological research in this field is insufficient to inform evidence-based guidance. Future research should aim to explore the wider psychological and criminal justice-based literature (e.g., memory retrieval and cognitive bias) to investigate what could be applicable to cold case investigations.