Co-offending network analysis in practice

Co-offending networks analysis contributes to predictive policing by detecting hidden links and predicting potential links among offenders. In this section, we introduce important applications of co-offending networks analysis in predictive policing that are covered in this research.

Organised crime group detection

Organised crime is a major international concern. Organised crime groups produce disproportionate harm to societies, and an increasing volume of violence is related to their activities. Because the primary aim of organised crime groups is gaining material benefit, they try to access to resources that can be profitably exploited. In terms of economic-related crimes (e.g., credit and debit card fraud), organised crime costs tax payers billions of dollars per year.

Understanding the structure of organised crime groups and the factors that impact on it is crucial to combat organised crime. There are several possible perspectives how to define the structure of organised crime groups, but recent criminological studies are increasingly focusing on using social network analysis for this purpose. The idea of using social network analysis is that links between offenders and subgroups of an organised crime group are critical determinant of the performance and sustainability of organised crime groups.

Confronted with a bewildering diversity of characteristics referred to in existing definitions of organised crime and criminal organisations, the conceptual model itself appears not clearly rendered in the literature. Striving for a definition that is general and open, a potential source is the criminal code, although this depends on a specific country. For instance, a baseline definition of criminal organisation is provided by the Criminal Code of Canada:

In Canada a criminal organization is a group, however organized that: (a) is composed of three or more persons in or outside Canada; and (b) has as oneof its main purposes or main activities the facilitation or commission of one or more serious offences, that, if committed, would likely result in the direct or indirect receipt of a material benefit, including a financial benefit, by the group or by any one of the persons who constitute the group. The definition further specifies that it excludes a group of three or more persons that has formed randomly for the immediate commission of a single offence.

(Section 467.1(1) of the Criminal Code of Canada)

Looking for a quantitative definition, in an attempt to measure organised crime, van der Heijden (1996) proposes a number of common characteristics:

1 Collaboration of more than two people;
2 Commission of serious criminal offences (suspected);
3 Determined by the pursuit of profit and/or power;
4 Each having their own appointed tasks;
5 For a prolonged or indefinite period of tune;
6 Using some form of discipline and control;
7 Operating across borders;
8 Using violence or other means suitable for intimidation;
9 Using commercial or business-like structures;
10 Engaged in money laundering;
11 Exerting influence on politics, the media, public administration, judicial authorities, or economy.

According to van der Heijden (1996), for any criminal group to be categorised as organised crime it needs to have at least six of these characteristics, where items 1, 2, and 3 are obligatory, thus adding three more characteristics. A major study in the Netherlands (Fijnaut, 1998, p. 27) mentions great variations in collaborative forms of organised crime and concludes that

the frameworks need not necessarily exhibit the hierarchical structure or meticulous division of labor often attributed to mafia syndicates. Intersections of social networks with a rudimentary division of labor have also been included as groups in the sub-report on the role of Dutch criminal groups, where they are referred to as cliques.

An impressive collection of definitions of organised crime specific for various countries, comprising more than individual 150 entries in total, has been gathered by von Lampe (2019). In addition, this collection also includes comments on how to define organised crime, and definitions by prominent individuals and government agencies, for instance, such as the Federal Brueau of Investigation (FBI). Not included though are definitions of the term ‘organised crime group'. Given the abstract nature and informal language of these definitions, it is not clear at all how and to what extent one may utilise this resource for defining organised crime in precise computational and/or mathematical tenus. The use of big data and its corresponding analytic techniques come into play here because various forms of law enforcement data can be used to show how offenders interact from the ground up and identify potentially organised behaviour’ (using all of the available data), rather than imposing a definition a priori and then searching for interactions that are consistent with that definition.