Criminologists have devoted surprisingly little attention to criminal investigation issues. This is understandable given the difficulties faced when performing empirical research into this subject. Getting access to confidential data from police and security services and disclosing such findings in scientific publications remains a challenge.
However, knowledge about investigative practices and their effects is essential for current debates about the legitimacy of new investigative methods and related privacy violations. This special issue contains contributions from authors who were able to connect research and science with criminal investigation practices. The contributions concern relevant topics, such as interrogation methods, social network analysis in criminal investigations, investigation of terrorist activities, sexual offenses, and private investigations. With these contributions, this special issue illustrates how empirical research into criminal investigation practices can be executed, and what new insights this provides.

This study aims to provide more knowledge on the extent to which criminal investigators are able to influence suspects’ statement. For this purpose, 166 observed interrogations covering the whole interrogation were analyzed. Based on these longitudinal data Structural Equation Modeling was used to examine the extent to which interrogation tactics mediate the changing statement between the start and the end of the interrogation. The results show that particularly suspects who give a statement on personal affairs at the beginning of the interrogation change their statement. Manipulating techniques are used more often when suspects are silent and confrontational techniques are used more often when suspects declare about the crime. Only confrontational techniques seem to contribute to changes in suspects’ statement. Accusatory interrogation tactics do not mediate the relationship between the statement given at the beginning of the interrogation and the change in statement. It can be concluded that suspects who are silent at the beginning of the interrogation or who declare about the crime in most cases don’t change their statement and that with using accusatory interrogation techniques criminal investigators seem to be unable to influence their statement.

Social network analysis (SNA) has taken its place in the field of criminology, although among Dutch criminologists the emphasis remains on conceptual contributions. Meanwhile, the world of criminal investigation and intelligence has witnessed the development of a blossoming SNA-practice. The emergence of big data makes SNA an indispensable tool to exploit the oceans of data in a meaningful way. Unfortunately, when it comes to employing SNA, academia and the investigations and intelligence domains remain separated. While Dutch analysts adopt scientific ideas and concepts, they rarely contribute to the body of literature; confidential SNA reports remain inaccessible. Shedding light on over forty SNA related internal police studies, this article bridges the gap between Dutch academic criminologists and ‘pracademics’ in law enforcement.

Since 2007 the police and the public prosecution service in the Netherlands can apply special investigative powers in case of ‘indications’ of a terrorist offense. To investigate signs of terrorism, a suspicion is no longer needed. The underlying assumption behind this extension is that the ‘old’ legislation offers insufficient opportunities to investigate signs of terrorism in an early phase. In this article we examine this assumption about the action space of investigating officers. For the period 2007-2011, we examined how investigating officers responded to signs of terrorism in practice, what investigative powers they used, and how they – as street level bureaucrats – handled their discretionary authority. The research shows that police and judiciary officials are very well able to investigate signs of terrorism with the already existing powers, and that they have made little use of the new ‘indications’ criterion

Eleven Teams against Child Abuse Images and Transnational Child Sex Offences (TBKKs) are operating within the Dutch National Police Force. This study provides an in-depth analysis of the resilience of criminal investigators working in these teams and how they perceive and cope with daily work stressors. Observational studies within five TBKKs and 35 semi-structured interviews with child pornography investigators revealed that managing their heavy caseloads, classifying abusive images, dealing with suspects and conducting home searches can sometimes be (very) challenging. Despite these demanding work aspects, investigators experience low levels of stress. By employing emotional detachment, self-reflection, workload regulation, social support and meaningfulness, they overcome the stress of investigating internet child exploitation. However, successful implementation of these resilience-enhancing strategies depends on the availability of several individual and organizational resources. To reduce the risk of health problems and to stimulate positive functioning, these resources require permanent investment from police management and investigators themselves.

In this article data derived from observations and interviews are used to examine private methods of investigation as used by corporate security providers in the Netherlands, and the private settlement options which follow those investigations. It is argued that, rather than leadership being exercised by public actors and institutions (police, prosecutors, criminal courts and also civil courts), those actors are selectively and strategically mobilised by corporate security, on behalf of their private sector clients. Corporate security and its clients have a ‘pick and choose’ approach when searching for an optimal solution for the incident at hand (forum shopping).

Traditionally, the Dutch penal judge needs to determine whether the suspect has committed the crime for which he is being prosecuted. This is generally done by accumulating incriminating evidence. Recently, it has been argued that this accumulation fosters the risk of a miscarriage of justice. Alternatively, the judge may want to rely on a Bayesians analysis of the evidence. Particularly, diagnostic values for each piece of evidence must be established. Therefore, it must be investigated how well the evidence fits in the primary and in alternative scenarios. This approach is discussed in this contribution.