Introduction: the criminology of Carlo Morselli

The idea that social relationships are central to the understanding of human phenomena draws its roots from Jacob Moreno’s work in 1934. He suggested that social ties between youths could explain a series of runaways in an American school for girls. That contribution, among others made at about the same time, paved the way for social network analysis (SNA), a set of methods and approaches that studies dyadic relationships and their connections to other dyads in the same network (Scott & Carrington, 2011). SNA has by now proven to be a fruitful way to understand a variety of phenomena, especially in sociology (Borgatti, Mehra, Brass, Labianca, 2009). Surprisingly enough, SNA was not widely adopted in criminology until the end of the 20 century (McGloin & Kirk, 2010), even if the notion that individuals are interdependent could be found in specific contexts, such as the study of victims and offenders in the context of domestic violence, for example, (Beck, Newton, Berk, 1986). It took researchers like Carlo Morselli to apply the principles of SNA and graph theory to criminological objects (see, Morselli (2009) for a review). As a researcher, Morselli embodied SNA: he was a so-called ‘broker’ in his network of social scientists, linking dozens of excellent researchers that he collaborated with, directly or not. Granovetter’s (1973) showed that ‘weak ties’ – or acquaintances – were important in the diffusion of new ideas, and Morselli put that insight to practice in criminology. He started with discussions about the sociology of deviance with his mentor, Pierre Tremblay, and turned it into a research agenda that covered a wide range of topics, from criminal achievement (Morselli & Royer, 2008; Morselli, Tremblay, McCarthy, 2006) to organised crime (Morselli, 2009; 2010). Both the editors of this issue had the opportunity to work with Carlo Morselli, even if, at the time, we worked on completely different topics: the social organisation of cyberoffenders for David Décary-Hétu, and international drug trafficking for Rémi Boivin. Morselli brought us to use similar methods and find commonalities. When we started discussing the production of a special issue to commemorate the legacy of Carlo Morselli in criminology, we were surprised by the number and diversity of researchers that wanted to contribute. Of course, we expected positive responses from Morselli’s social ties within his own institution, the Université de Montréal. These included the editorial team, Frédéric Ouellet and Martin Bouchard, all alumnis of the School of Criminology of the Université de Montréal. We also received dozens of propositions from across the world. The production of this special issue, along with the two others that will