Abstract
This research contributes to understanding those factors associated with solving difficult murder cases and elucidating the decision-making processes of Senior Investigating Officers (SIOs). Relatively little has been written within this field and the present thesis argues that aspects of the murder itself, police investigative procedures and the management style of the SIOs, contributes to the solving of cases. Natural Decision-making provided the theoretical framework for this research with studies designed to flesh out the knowledge required and reasoning skills needed by the SIOs. The thesis explores the decision-making processes underpinning successful resolution of murder cases. The research used a mixed method approach combining qualitative accounts from 31 experienced detectives and quantitative analyses of their 166 murder cases, together with documentary analyses of historic cases to map the evolution of modern investigative practice. The practical outcomes of this research are its contribution to systematising police murder investigations. Study One explores the lessons learnt from previous murder enquiries and charts how mistakes have contributed to developing techniques and refining the methods of murder investigations. Study Two explores current practice in major inquiries within the Metropolitan Police Service and presents a flowchart of the key phases. The management style of SIOs was elucidated in Study Three and the concepts of starburst, phasing and investigative thinking were found helpful concepts in describing the investigative process. Seven broad themes were identified as solving strategies from which 41 individual factors were established. Study Four involved the secondary analysis of 166 archived cases stored in the Home Office Major Enquiry System (Holmes). Regression analyses of a combined data set showed statistically significant factors associated with both the solving of cases (i.e. number of police investigative tactics used and features of the murder) and the time taken to solve a murder (i.e. type of investigative tactics and style of the SIO). The discussion chapter outlines the necessary investigative processes related to different types of murder whilst the final chapter draws some conclusions and makes recommendations for good practice.