Uncertainty and the case of police constable 'Tiger' Tsui Po-ko

A rare open fire event in Hong Kong between police officers resulted in the death of two constables and sparked intense media interest about what caused the incident. At the request of the Hong Kong Police the author helped review the investigation of this intra-police homicide. After a coronial inquest two earlier homicides were also linked to the shooting and subsequently resolved. Through this unusual case this paper explores how efforts to reduce uncertainty help clarify the limits of forensic and behavioural analysis. Uncertainty over motivations and the mental health of the suspect led to different psychiatric, psychological, behavioural profiling and criminological explanations of this complex event. This case study compares the different approaches to uncertainty in the expert opinion offered by these disciplines. The paper concludes by advocating the explicit recognition of uncertainty as a means of advancing an investigation.