This thesis seeks to address the complex forms assumed by the problem of human trafficking in the contemporary world and in particular to analyse and overcome certain identified shortcomings in existing models of intervention. It begins by locating the problem historically through its foundations in slavery, and explores the incomplete nature of the abolition of that institution. These observations provide the context for the emergence of contemporary forms of exploitation. The complexity of the problem of human trafficking is reflected in the variety of approaches to intervention thus far attempted and in the lack of consensus among stakeholders concerning the effectiveness of competing models. The tendency towards institutional failure in current approaches, and the consequent growth of the trafficking phenomenon are compounded by the ability of criminal networks to infiltrate and corrupt the very systems that are meant to safeguard vulnerable populations. This thesis argues that the shortcomings of existing models are themselves evidence that one of the foundational reasons for the emergence of human trafficking as a networked global crime is the security deficit created by the replacement of the structures of state with criminal networks embedded within communities. These observations are supported by empirical evidence in the form of i) a detailed review of records relating to a number of prosecutions and ii) first-hand observations and interviews with officials and civil society organisations in India, the United Kingdom and the Netherlands. I argue, in conclusion, that the evolution of models of intervention, leading to the creation of a preferred multidisciplinary model, show that this security deficit is best countered by emergent partnerships between the structures of the state, communities and civil society groups. Such innovations prefigure new hybrid structures, which offer a degree of hope for holistically tackling common global problems and networked crimes such as human trafficking.

This dissertation employs network analysis in the study of crime. This methodological approach is the common factor in the three studies included in the dissertation. The overall objective is to see what the network analytical approach has to offer to the study of different aspects of crime. The data employed in the analyses comprise offences registered by the Stockholm police that have also been tied to a suspect. In the study of supporter violence, this data is supplemented with information on offences for which persons have been convicted. The first study focuses on supporters whom the police regard as particularly prone to violence. The criminal networks of these supporters are studied for the years 1994-1997. The supporters are also compared with their known co-offenders. The study shows that a large proportion of the crimes committed by the supporter group are violent offences. For the most part, the supporters’ are involved in loose-knit criminal networks and in general their co-offenders are more criminally active than they are themselves. Certain of the supporters appear to constitute links between the supporter group and more serious criminals active in the Stockholm area. The second study examines the ethnic composition of networks of youths suspected of violent offences during 1995, as well as the persons against whom these young people commit their offences. The study shows that the registered violent crime committed by youths in Stockholm is characterised by ethnic heterogeneity. The conclusion is that whom these youths commit crimes with and against respectively is primarily decided by factors other than the youths’ ethnic background. The third study focuses on gender factors relating to networks of youths suspected of violent offences during the course of 1995. The study compares the structure of the registered violent offending of girls and boys respectively. The study is based on the theoretical assumption that acts of violence may constitute an opportunity to construct gender. The study shows that apart from previously established differences in the levels of violent activity presented by girls and boys respectively, the structure of their violent offending is strikingly similar. A further conclusion is that the violent crime of girls and boys is characterised by sexual homogeneity. This is seen as indicating that gender construction by means of violent crime primarily takes place between boys and other boys and between girls and other girls. The assertion of superiority that violence involves is thus most often directed at persons of the same sex, girls primarily attempt to assert superiority over other girls, and boys over other boys. The dissertation also contends that as a method, network analysis has made several important contributions to the study of the research questions. In all three pieces of research, network analysis has made possible important insights into the phenomena under study, which would not have been identified had alternative methodological approaches been employed. / <p>Alternativ titel: Tre perspektiv på brottsliga nätverk: Supporterbråk, etnicitet och genus</p>

This thesis seeks to extend the application of Social Network Analysis (SNA) to temporal graphs, in particular providing new insights for the understanding of covert networks. The analyses undertaken reveal informative features and properties of individuals' affiliations under covertness that also illustrate how both individuals and events influence the network structure. The review of the literature on covert networks provided in the initial two chapters suggests the presence of some ambiguities concerning how authors define structural properties and dynamics of covert networks. Authors sometimes disagree and use their findings to explain opposite views about covert networks. The controversy in the field is used as a starting point in order to justify the methodological application of SNA to understand how individuals involved in criminal and illegal activities interact with each other. I attempt to use a deductive approach, without preconceived notions about covert network characteristics. In particular, I avoid considering covert networks as organisations in themselves or as cohesive groups. I focus on individuals and their linkages constructed from their common participation in illicit events such as secret meetings, bombing attacks and criminal operations. In order to tackle these processes I developed innovative methods for investigating criminals' behaviours over time and their willingness to exchange tacit information. The strategy implies the formulation of a network model in order to represent and incorporate in a graph three types of information: individuals, events, and the temporal dimension of events. The inclusion of the temporal dimension offers the possibility of adopting a more comprehensive theoretical framework for considering individuals and event affiliations. This thesis expands the analysis of bipartite covert networks by adopting several avenues to explore in this perspective. Chapter 3 proposes a different way to represent two-mode networks starting from the use of line-graphs, namely the bi-dynamic line-graph data representation (BDLG), through which it is possible to represent the temporal evolution of individual's trajectories. The following chapter 4 presents some reflections about the idea of cohesion and cohesive subgroups specific to the case of two-mode networks. Based on the affiliation matrices, the analysis of local clustering through bi-cliques offers an attempt to analyse the mechanism of selecting accomplices while taking into account time. Chapter 5 is concerned with the concept of centrality of individuals involved in flows of knowledge exchanges. The theoretical and analytical framework helps in elaborating how individuals share their acquired hands-on experiences with others by attending joint task activities over time. Chapter 6 provides an application of the approaches introduced in the preceding chapters to the specific case of the Noordin Top terrorist network. Here, the knowledge of experience flow centrality measure opens up a new way to quantify the transmission of information and investigate the formation of the criminal capital. Finally, the last Chapter 7 presents some future research extensions by illustrating the versatility of the proposed approaches in order to provide new insights for the understanding of criminals' behaviours.

Genom en systematisk litteraturöversikt i kombination med en intervju är syftet med denna uppsats att försöka beskriva varför den sociala nätverksanalysen är lämplig i brottsutredningssammanhang samt hur den sociala nätverksanalysen används i brottsutredningar. Tanken är också att översikten ska kunna bidra till att se vilka möjligheter det finns att praktiskt utveckla metoden. Det finns en hel del forskning kring både social nätverksanalys (SNA) som metod och som teori och det används idag inom en mängd olika områden. Som teori handlar SNA om hur vi människor är sociala varelser som påverkar varandra i de tankar vi har och i de val som vi gör. Som metod är SNA istället olika matematiska uträkningar som kan användas för att beskriva mänskliga relationer. Inom kriminologin är SNA relativt nytt trots att brott i sig ofta är ett ”nätverksfenomen”. Flera kriminologiska teorier trycker också på betydelsen av att den egna brottsligheten har ett samband med de personer som vi umgås med. Resultatet visar att det finns klara fördelar med att använda sig av SNA i en brottsutredning, strukturer och nyckelpersoner kan identifieras, något som inte alltid hade kunnat ske utan teknikens hjälp. Den data som i utredningssammanhang används till nätverksanalyser är vanligtvis kvantitativa data, exempelvis telefontrafik. Olika typer av data kan ge väldigt olika resultat och blir det fel i datainsamling kan det sabotera för hela analysen. Det behövs mer teoretisk forskning kring SNA för att den som metod ska kunna appliceras på kriminologisk teori och på sikt även kunna användas bättre i utredningssammanhang. Ett stort problem med att forska om metoden är att den kvantitativa datan kan vara svår att få tag på, det finns därför väldigt lite litteratur om hur social nätverksanalys kan användas i brottsutredningar. / With a systematic literature review and an interview, the aim of this essay is to try to describe how the social network analysis (SNA) is used in criminal investigations. Hopefully, the essay can also help in pointing out why future research is needed and in what direction that research should go. As a theory, SNA focuses on man as a social being and how we affect each other in the way we think and act. As a method SNA is a number of mathematical computations that aims to explain relationships. There is a large amount of research about social network analysis, both as a theory and as a method but in the criminological field SNA is still relatively new. That is surprising as many criminological theories focuses on the importance of the people we engage with and our own delinquency. The result in this essay shows that there are many advantages with using SNA in a criminal investigation, structures and key-persons becomes more visible which sometimes is hard without technology. Different types of data can generate very different results and if something goes wrong in the collection of data it can sabotage the entire analysis. There is a need for more theoretical research on SNA so that it, as a method, can be applied to criminological theory and later to criminal investigations. There is a big problem when doing research about social networks, the access to network-data. It is very hard to collect and is usually only available to police-officers or other qualified groups. Therefore the amount of literature in the subject is limited.

The Swedish Police Authority currently categorise 61 urban areas in Sweden as vulnerable areas, where there is an increased risk of becoming a victim of crime or violence to both females and males living in those areas. In these places the feeling of insecurity and the lack of trust and confidence in the judiciary system is more common than in other urban parts of Sweden. Due to this negative trend and development local power factors have evolved, and the risk of parallel social structures enforced by criminal activity and violent extremism is higher than in other places in Sweden. This thesis investigates the connection between Swedish criminal networks and violent Islamic extremism to create a better understand of why individuals from the vulnerable areas in Sweden join criminal networks and, or violent Islamic extremist groups

The thesis was aimed to investigate the structure of a criminal network and how the EncroChat-communication- and co-offending-structure differs. To study this, a network analytical method was applied that resulted in four networks: co-offending according to the verdict, co-offending according to the prosecution, Encrochat-communication and a network where these three networks were merged. The results showed that the cooffending networks obtained a more compact composition than the EncroChatcommunication network. All networks had a dense core containing the most central actors, although some exceptions existed in the co-offending networks. The results of the network analysis indicated that the actors who committed the most crimes also communicated the most. The results also showed a partly different composition of other prominent actors in the network analysis than what the prosecutor presented. Therefore, network analysis can be used as an extra dimension in law enforcement work due to its function in identifying structures.

Nesta tese investigam-se três pontos ligados a fragilidades topológicas de grafos e suas aplicações a redes complexas reais e, em especial, a redes de relacionamentos criminais. Na primeira etapa, apresenta-se in abstracto um método inédito e eficiente de fragmentação de redes complexas por módulos. O procedimento identifica em primeiro lugar comunidades topológicas por meio da qual a rede pode ser representada usando algoritmos heurísticos de extração de comunidades. Então, somente os nós que participam de ligaçõees inter-comunitaárias são removidos em ordem decrescente de sua centralidade de intermediação. Ilustra-se o método pela aplicação a uma variedade de redes reais nas áreas social, de infraestrutura, e biológica. Mostra-se que a abordagem por módulos supera ataques direcionados a vértices baseados somente no ordenamento de índices de centralidade, com ganhos de eficiência fortemente relacionados à modularidade da rede.No segundo momento, introduzem-se os conceitos de robustez e fragilidade de redes generalizadas para avaliar o quanto um determinado sistema se comporta frente a ataques incompletos. Ainda, avalia-se o desempenho (relação entre robustez e custo computacional) de diversos ataques sequenciais e simultâneos a redes modulares por meio de uma medida empírica que chamamos de performance. Mostra-se por meio de redes artificiais de referência e de redes reais que para sistemas altamente modulares a estratégia de fragmentação por módulos apresenta um desempenho até 10 vezes superior aos demais ataques. Na última etapa, explora-se com maior profundidade a natureza subjacente de redes reais de relacionamentos criminais. Apresenta-se uma rede única e sem precedentes construída pela Polícia Federal Brasileira consistindo de mais de 35.000 relacionamentos entre 24.000 indivíduos. Os dados foram coletados entre abril e agosto de 2013 e consistem em informações fornecidas diretamente pelos investigadores responsáveis de cada caso. O sistema apresenta características típicas de redes sociais, porém é bem mais “escuro"que o comportamento típico, com baixos níveis tanto de densidade de arestas quanto de eficiência de rede. Além do mais, o sistema é extremamente modular o que implica ser possível desmantelar toda a rede de crimes federais brasileiros com a remoção de aproximadamente 2% dos indivíduos escolhidos conforme a prescrição do método modular. Também, a rede é controlável no sentido da teoria matemática de controle, significando que com acesso a aproximadamente 20% dos nós é possível, em tese, levar qualquer variável dinâmica de um estado inicial a um estado final arbitrário em um tempo finito. Exibi-se tambám uma análise topológica e de fragilidades de uma segunda rede criminal relacionada a investigações da Polícia Federal. Trata-se de um fórum online destinado à prática de crimes cibernéticos na chamada camada profunda da internet (deep web). (Continuação ) Após a coleta dos dados foi possível construir uma rede de relacionamentos com quase 10.000 indivíduos. Comparou-se, entãoo, a estratégia usada de fato pela Polícia Federal durante a Operação Darknet com a previsão teórica de ataques topológicos à rede criminal e mostrou-se que ataques dirigidos por grau teriam fragmentado o sistema de maneira quase 15 vezes mais eficiente. Por outro lado, esta rede não é modular apesar de novamente apresentar uma arquitetura mais “escura" que o usual. Por termo, demonstra-se que os ataques por arestas estão diretamente relacionados ao aprisionamento enquanto que a ressocialização e/ou morte dos indivíduos é melhor interpretada como a remoção por vértices. Destarte, comprovou-se que de um ponto de vista topológico a ressocialização é de fato mais eficiente em reduzir a criminalidade do que o aprisionamento. Contudo, na rede de crimes federais estudada essa diferenca é muito pequena, de tal modo que ambas as políticas poderiam, em tese, ser aplicadas a fim de se combater eficientemente o sistema criminoso. / In this thesis we investigate three points connected to topological fragilities of graphs and their applications to real complex networks and, in particular, to networks of criminal relationships. In the first step, we present an unprecedented and efficient method of fragmentation of complex networks by modules. Firstly, the procedure identifies topological communities through which the network can be represented using heuristic communities extraction algorithms. After that, only the nodes that bridge communities are removed in descending order of their betweenness centrality . We illustrate the method by the applying it to a variety of real networks in the social, infrastructure, and biological fields. We show that the modular approach outperforms attacks traditional attacks based only on the ordering of centrality indexes, with efficiency gains strongly related to the modularity of the network. In the second moment, we introduce the concepts of generalized robustness and fragility of networks to evaluate how much a certain system behaves in the face of incomplete attacks. Also, we evaluate the relation between robustness and computational cost of several sequential and simultaneous attacks to modular networks by means of an empirical measure that we call performance. In this sense, we show through artificial and real networks that for highly modular systems the strategy of fragmentation by modules presents a performance up to 10 times superior to traditional attacks. In the last step, we explore in more depth the underlying nature of real networks of criminal relationships. We present a unique and unprecedented network built by the Brazilian Federal Police consisting of more than 35,000 relationships among 24,000 individuals. The data were collected between April and August 2013 and consist of information provided directly by the investigators responsible for each case. The system has typical characteristics of social networks, but is much "darker"than traditional social networks, with low levels of edge density and network efficiency. Moreover, the network is extremely modular which implies that it is possible to dismantle all the network of Brazilian federal crimes with the removal of approximately 2% of the individuals chosen according to the modular method. Also the network is controllable in the sense of the mathematical control theory, meaning that with access only to 20% of nodes it is possible, In theory, to take any dynamic variable from an initial state to an arbitrary final state in a finite time. We also show a topological analysis of a second criminal network related to Federal Police investigations. This is an online forum for cybercrime in the so-called deep web. After the data collection, it was possible to build a network of relationships with almost 10,000 individuals. We then compared the strategy actually used by the Federal Police during Operation Darknet with the theoretical prediction of topological attacks on the criminal network and showed that degree-based attacks would have fragmented the system almost 15 times more efficiently. On the other hand, this network is not modular despite presenting a "darker"architecture than usual. As a last result, this particular system is not controllable in practical terms. We finish the study by showing that edge attacks are directly related to the imprisonment whereas the resocialization and/or death of the individuals is better interpreted as the removal of vertices. Thus, we prove that from a topological point of view resocialization is in fact more efficient in reducing crime rates than imprisonment. However, in the network of federal crimes studied here this difference is very small, so that both policies could in theory be applied in order to combat effectively the criminal system.

Nesta tese investigam-se três pontos ligados a fragilidades topológicas de grafos e suas aplicações a redes complexas reais e, em especial, a redes de relacionamentos criminais. Na primeira etapa, apresenta-se in abstracto um método inédito e eficiente de fragmentação de redes complexas por módulos. O procedimento identifica em primeiro lugar comunidades topológicas por meio da qual a rede pode ser representada usando algoritmos heurísticos de extração de comunidades. Então, somente os nós que participam de ligaçõees inter-comunitaárias são removidos em ordem decrescente de sua centralidade de intermediação. Ilustra-se o método pela aplicação a uma variedade de redes reais nas áreas social, de infraestrutura, e biológica. Mostra-se que a abordagem por módulos supera ataques direcionados a vértices baseados somente no ordenamento de índices de centralidade, com ganhos de eficiência fortemente relacionados à modularidade da rede.No segundo momento, introduzem-se os conceitos de robustez e fragilidade de redes generalizadas para avaliar o quanto um determinado sistema se comporta frente a ataques incompletos. Ainda, avalia-se o desempenho (relação entre robustez e custo computacional) de diversos ataques sequenciais e simultâneos a redes modulares por meio de uma medida empírica que chamamos de performance. Mostra-se por meio de redes artificiais de referência e de redes reais que para sistemas altamente modulares a estratégia de fragmentação por módulos apresenta um desempenho até 10 vezes superior aos demais ataques. Na última etapa, explora-se com maior profundidade a natureza subjacente de redes reais de relacionamentos criminais. Apresenta-se uma rede única e sem precedentes construída pela Polícia Federal Brasileira consistindo de mais de 35.000 relacionamentos entre 24.000 indivíduos. Os dados foram coletados entre abril e agosto de 2013 e consistem em informações fornecidas diretamente pelos investigadores responsáveis de cada caso. O sistema apresenta características típicas de redes sociais, porém é bem mais “escuro"que o comportamento típico, com baixos níveis tanto de densidade de arestas quanto de eficiência de rede. Além do mais, o sistema é extremamente modular o que implica ser possível desmantelar toda a rede de crimes federais brasileiros com a remoção de aproximadamente 2% dos indivíduos escolhidos conforme a prescrição do método modular. Também, a rede é controlável no sentido da teoria matemática de controle, significando que com acesso a aproximadamente 20% dos nós é possível, em tese, levar qualquer variável dinâmica de um estado inicial a um estado final arbitrário em um tempo finito. Exibi-se tambám uma análise topológica e de fragilidades de uma segunda rede criminal relacionada a investigações da Polícia Federal. Trata-se de um fórum online destinado à prática de crimes cibernéticos na chamada camada profunda da internet (deep web). (Continuação ) Após a coleta dos dados foi possível construir uma rede de relacionamentos com quase 10.000 indivíduos. Comparou-se, entãoo, a estratégia usada de fato pela Polícia Federal durante a Operação Darknet com a previsão teórica de ataques topológicos à rede criminal e mostrou-se que ataques dirigidos por grau teriam fragmentado o sistema de maneira quase 15 vezes mais eficiente. Por outro lado, esta rede não é modular apesar de novamente apresentar uma arquitetura mais “escura" que o usual. Por termo, demonstra-se que os ataques por arestas estão diretamente relacionados ao aprisionamento enquanto que a ressocialização e/ou morte dos indivíduos é melhor interpretada como a remoção por vértices. Destarte, comprovou-se que de um ponto de vista topológico a ressocialização é de fato mais eficiente em reduzir a criminalidade do que o aprisionamento. Contudo, na rede de crimes federais estudada essa diferenca é muito pequena, de tal modo que ambas as políticas poderiam, em tese, ser aplicadas a fim de se combater eficientemente o sistema criminoso. / In this thesis we investigate three points connected to topological fragilities of graphs and their applications to real complex networks and, in particular, to networks of criminal relationships. In the first step, we present an unprecedented and efficient method of fragmentation of complex networks by modules. Firstly, the procedure identifies topological communities through which the network can be represented using heuristic communities extraction algorithms. After that, only the nodes that bridge communities are removed in descending order of their betweenness centrality . We illustrate the method by the applying it to a variety of real networks in the social, infrastructure, and biological fields. We show that the modular approach outperforms attacks traditional attacks based only on the ordering of centrality indexes, with efficiency gains strongly related to the modularity of the network. In the second moment, we introduce the concepts of generalized robustness and fragility of networks to evaluate how much a certain system behaves in the face of incomplete attacks. Also, we evaluate the relation between robustness and computational cost of several sequential and simultaneous attacks to modular networks by means of an empirical measure that we call performance. In this sense, we show through artificial and real networks that for highly modular systems the strategy of fragmentation by modules presents a performance up to 10 times superior to traditional attacks. In the last step, we explore in more depth the underlying nature of real networks of criminal relationships. We present a unique and unprecedented network built by the Brazilian Federal Police consisting of more than 35,000 relationships among 24,000 individuals. The data were collected between April and August 2013 and consist of information provided directly by the investigators responsible for each case. The system has typical characteristics of social networks, but is much "darker"than traditional social networks, with low levels of edge density and network efficiency. Moreover, the network is extremely modular which implies that it is possible to dismantle all the network of Brazilian federal crimes with the removal of approximately 2% of the individuals chosen according to the modular method. Also the network is controllable in the sense of the mathematical control theory, meaning that with access only to 20% of nodes it is possible, In theory, to take any dynamic variable from an initial state to an arbitrary final state in a finite time. We also show a topological analysis of a second criminal network related to Federal Police investigations. This is an online forum for cybercrime in the so-called deep web. After the data collection, it was possible to build a network of relationships with almost 10,000 individuals. We then compared the strategy actually used by the Federal Police during Operation Darknet with the theoretical prediction of topological attacks on the criminal network and showed that degree-based attacks would have fragmented the system almost 15 times more efficiently. On the other hand, this network is not modular despite presenting a "darker"architecture than usual. As a last result, this particular system is not controllable in practical terms. We finish the study by showing that edge attacks are directly related to the imprisonment whereas the resocialization and/or death of the individuals is better interpreted as the removal of vertices. Thus, we prove that from a topological point of view resocialization is in fact more efficient in reducing crime rates than imprisonment. However, in the network of federal crimes studied here this difference is very small, so that both policies could in theory be applied in order to combat effectively the criminal system.

Nesta tese investigam-se três pontos ligados a fragilidades topológicas de grafos e suas aplicações a redes complexas reais e, em especial, a redes de relacionamentos criminais. Na primeira etapa, apresenta-se in abstracto um método inédito e eficiente de fragmentação de redes complexas por módulos. O procedimento identifica em primeiro lugar comunidades topológicas por meio da qual a rede pode ser representada usando algoritmos heurísticos de extração de comunidades. Então, somente os nós que participam de ligaçõees inter-comunitaárias são removidos em ordem decrescente de sua centralidade de intermediação. Ilustra-se o método pela aplicação a uma variedade de redes reais nas áreas social, de infraestrutura, e biológica. Mostra-se que a abordagem por módulos supera ataques direcionados a vértices baseados somente no ordenamento de índices de centralidade, com ganhos de eficiência fortemente relacionados à modularidade da rede.No segundo momento, introduzem-se os conceitos de robustez e fragilidade de redes generalizadas para avaliar o quanto um determinado sistema se comporta frente a ataques incompletos. Ainda, avalia-se o desempenho (relação entre robustez e custo computacional) de diversos ataques sequenciais e simultâneos a redes modulares por meio de uma medida empírica que chamamos de performance. Mostra-se por meio de redes artificiais de referência e de redes reais que para sistemas altamente modulares a estratégia de fragmentação por módulos apresenta um desempenho até 10 vezes superior aos demais ataques. Na última etapa, explora-se com maior profundidade a natureza subjacente de redes reais de relacionamentos criminais. Apresenta-se uma rede única e sem precedentes construída pela Polícia Federal Brasileira consistindo de mais de 35.000 relacionamentos entre 24.000 indivíduos. Os dados foram coletados entre abril e agosto de 2013 e consistem em informações fornecidas diretamente pelos investigadores responsáveis de cada caso. O sistema apresenta características típicas de redes sociais, porém é bem mais “escuro"que o comportamento típico, com baixos níveis tanto de densidade de arestas quanto de eficiência de rede. Além do mais, o sistema é extremamente modular o que implica ser possível desmantelar toda a rede de crimes federais brasileiros com a remoção de aproximadamente 2% dos indivíduos escolhidos conforme a prescrição do método modular. Também, a rede é controlável no sentido da teoria matemática de controle, significando que com acesso a aproximadamente 20% dos nós é possível, em tese, levar qualquer variável dinâmica de um estado inicial a um estado final arbitrário em um tempo finito. Exibi-se tambám uma análise topológica e de fragilidades de uma segunda rede criminal relacionada a investigações da Polícia Federal. Trata-se de um fórum online destinado à prática de crimes cibernéticos na chamada camada profunda da internet (deep web). (Continuação ) Após a coleta dos dados foi possível construir uma rede de relacionamentos com quase 10.000 indivíduos. Comparou-se, entãoo, a estratégia usada de fato pela Polícia Federal durante a Operação Darknet com a previsão teórica de ataques topológicos à rede criminal e mostrou-se que ataques dirigidos por grau teriam fragmentado o sistema de maneira quase 15 vezes mais eficiente. Por outro lado, esta rede não é modular apesar de novamente apresentar uma arquitetura mais “escura" que o usual. Por termo, demonstra-se que os ataques por arestas estão diretamente relacionados ao aprisionamento enquanto que a ressocialização e/ou morte dos indivíduos é melhor interpretada como a remoção por vértices. Destarte, comprovou-se que de um ponto de vista topológico a ressocialização é de fato mais eficiente em reduzir a criminalidade do que o aprisionamento. Contudo, na rede de crimes federais estudada essa diferenca é muito pequena, de tal modo que ambas as políticas poderiam, em tese, ser aplicadas a fim de se combater eficientemente o sistema criminoso. / In this thesis we investigate three points connected to topological fragilities of graphs and their applications to real complex networks and, in particular, to networks of criminal relationships. In the first step, we present an unprecedented and efficient method of fragmentation of complex networks by modules. Firstly, the procedure identifies topological communities through which the network can be represented using heuristic communities extraction algorithms. After that, only the nodes that bridge communities are removed in descending order of their betweenness centrality . We illustrate the method by the applying it to a variety of real networks in the social, infrastructure, and biological fields. We show that the modular approach outperforms attacks traditional attacks based only on the ordering of centrality indexes, with efficiency gains strongly related to the modularity of the network. In the second moment, we introduce the concepts of generalized robustness and fragility of networks to evaluate how much a certain system behaves in the face of incomplete attacks. Also, we evaluate the relation between robustness and computational cost of several sequential and simultaneous attacks to modular networks by means of an empirical measure that we call performance. In this sense, we show through artificial and real networks that for highly modular systems the strategy of fragmentation by modules presents a performance up to 10 times superior to traditional attacks. In the last step, we explore in more depth the underlying nature of real networks of criminal relationships. We present a unique and unprecedented network built by the Brazilian Federal Police consisting of more than 35,000 relationships among 24,000 individuals. The data were collected between April and August 2013 and consist of information provided directly by the investigators responsible for each case. The system has typical characteristics of social networks, but is much "darker"than traditional social networks, with low levels of edge density and network efficiency. Moreover, the network is extremely modular which implies that it is possible to dismantle all the network of Brazilian federal crimes with the removal of approximately 2% of the individuals chosen according to the modular method. Also the network is controllable in the sense of the mathematical control theory, meaning that with access only to 20% of nodes it is possible, In theory, to take any dynamic variable from an initial state to an arbitrary final state in a finite time. We also show a topological analysis of a second criminal network related to Federal Police investigations. This is an online forum for cybercrime in the so-called deep web. After the data collection, it was possible to build a network of relationships with almost 10,000 individuals. We then compared the strategy actually used by the Federal Police during Operation Darknet with the theoretical prediction of topological attacks on the criminal network and showed that degree-based attacks would have fragmented the system almost 15 times more efficiently. On the other hand, this network is not modular despite presenting a "darker"architecture than usual. As a last result, this particular system is not controllable in practical terms. We finish the study by showing that edge attacks are directly related to the imprisonment whereas the resocialization and/or death of the individuals is better interpreted as the removal of vertices. Thus, we prove that from a topological point of view resocialization is in fact more efficient in reducing crime rates than imprisonment. However, in the network of federal crimes studied here this difference is very small, so that both policies could in theory be applied in order to combat effectively the criminal system.

Based on six-years ethnographic research, this thesis provides an in-depth account of a contemporary British drug market. The study follows a group of twenty-five friends, termed The Lads, during their transition from late-adolescence (16-22) through to early adulthood (22-28). This was a critical stage in their life course; it was a time when many had begun advancing into the world of work and business entrepreneurship, in search of their chosen career. Yet it was during this time that two key developments occurred: bulk volumes of illicit drugs became available to The Lads through credit and the UK experienced several years of economic recession and stagnation. The economic constraints The Lads encountered during this time prompted many to become involved in the trafficking of illegal drugs. Though their entry into the markets was not necessarily motivated out of absolute need or poverty, the experience of low-paying salaries, the loss of work and income, and the inability to secure legitimate investment capital, all made drug dealing an alluring source of untaxed revenue, available as and when needed. This study assesses the practices of this cohort of closed-market drug dealers, who capitalised on their expansive social networks as a means of trafficking a variety of illegal substances at the time of these two developments. During the course of the research their involvement came to span several stages of the supply chain, including: mid-level wholesale brokerage, import/export, wholesale, and retail (i.e. to the end-users). The study addresses various structural elements of their trade, including drug purchasing and selling, the assessment and mitigation of risks in relation to law enforcement, and the use of informal credit (i.e. ‘fronting’) as one of the principle facilitating factors of The Lads’ various trade networks. A variety of data collection methods were employed over many years to garner a depth of understanding and appreciation difficult to achieve in the study of active offenders. The data comprises of life narratives, observations, interview data and economic data. The findings offer some new insight into: the kinds of people who deal drugs; what characteristics they share; how they function as traders; what motivates them to either enter or exit the trade, and what social structures influence their offending careers?These young men were not the archetypal drug dealer: they were neither predatory nor territorial. They were ambitious and hard working. Drug dealing was simply a shortcut to the lifestyle they aspired to; it was a source of capital; a means of funding their studies; a ‘means to an end’. To these young men, drug dealing was just another form of work: a bad job that paid a good salary.