This paper provides a comparison between four methodologies that assist criminal investigators in homicide investigations. The Person of Interest Priority Assessment Tool, Trace Investigate and Evaluate, Rasterfahndung, and Analysis of Competing Hypotheses are compared on their performance in the collection, prioritization, and elimination phase of homicide cases in today’s digital era. Three recent Dutch homicide cases are used. The use of categories during collection can assist criminal investigators in the early inclusion of the perpetrator into the investigation, however, in this digital era, the number of persons of interest becomes too large to humanly handle. All four methodologies use techniques to assign weight to pieces of evidence; further research is required to evaluate the effectiveness of these techniques when the amount of pieces of evidence explodes. The use of pre-set elimination categories shows the least promising result leaving most persons of interest not-eliminated by the currently used methodologies.

Homicide investigators in the digital era have access to an increasing amount of data and the processing of all persons of interest and pieces of evidence has become nearly impossible. This paper describes the development and evaluation of a case-specific element library (C-SEL) that can be used to incorporate and prioritize persons of interest in homicide investigations. In a survey, 107 experts in the field of criminal investigation assigned an initial score to the elements. Each element was extended with underlying factors that can be used to adjust the initial score based on the relevance and credibility of the source. A case study was conducted using three Dutch real-world cases to evaluate the methodology. The results look promising and are better than four methodologies currently used in practice.

In this paper two Bayesian approaches and a frequency approach are compared on predicting offender output variables based on the input of crime scene and victim variables. The K2 algorithm, Naïve Bayes and frequency approach were trained to make the correct prediction using a database of 233 solved Dutch single offender/single victim homicide cases and validated using a database of 35 solved Dutch single offender/single victim homicide cases. The comparison between the approaches was made using the measures of overall prediction accuracy and confidence level analysis. Besides the comparison of the three approaches, the correct predicted nodes per output variable and the correct predicted nodes per validation case were analyzed to investigate whether the approaches could be used as a decision tool in practice to limit the incorporation of persons of interest into homicide investigations. The results of this study can be summarized as: the non-intelligent frequency approach shows similar or better results than the intelligent Bayesian approaches and the usability of the approaches as a decision tool to limit the incorporation of persons of interest into homicide investigations should be questioned.

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