This report discusses the concept of professionalizing investigation and its significance in criminal cases. It focuses on a case study of Sian O' Callaghan and Becky Godden Edwards, highlighting the critical assessment of the police investigation. The report also examines the role of the investigating officer and the improvements that could have been made. It provides a step-by-step analysis of the investigations and the reasons behind certain decisions. The report concludes with the outcomes of the case and the importance of following guidelines and procedures in criminal investigations.