By David Pérez Esparza

This thesis aims to explain why, against the background of a fairly global crime drop, violence and crime increased in Mexico in the mid-2000s. Since most classical hypotheses from criminological research are unable to account satisfactorily for these trends, this study tests the explanatory power of a situational hypothesis as the main independent variable (i.e. the role of opportunity). In particular, this involves testing whether the rise in violence can be explained by an increase in the availability of illegal weapons in Mexico resulting from policy changes and rises in gun production in the bordering U.S. To conduct this study, the thesis develops and implements an ad hoc analytic strategy (composed of six steps) that helps to examine each gun market (i.e. pistols, revolvers, rifles, and shotguns) both in the supply (U.S.) and in the illegal demand for firearms (Mexico). Following this market approach, the study finds that patterns of gun production in the U.S. temporally and spatially coincide with the patterns of gun confiscation (and violent crime) in Mexico. More specifically, analyses suggest that changes in illegal gun availability (across time and space) provide a better explanation for the observed difference in state-level homicide in Mexico than traditional hypotheses. The thesis presents additional analyses in favour of the situational hypothesis (through triangulation) and reports the findings of novel interviews with law enforcement officers with experience on gun trafficking in the U.S.-Mexico context. The study concludes by reviewing the key findings concerning the illicit markets between Mexico and the U.S., their theoretical and policy implications, as well as possible avenues for future research.

London: University College London, 2019. 389p.

By Jess T. Ford

In recent years, violence along the U.S.-Mexico border has escalated dramatically, due largely to the Mexican government's efforts to disrupt Mexican drug trafficking organizations (DTO). U.S. officials note the violence associated with Mexican DTOs poses a serious challenge for U.S. law enforcement, threatening citizens on both sides of the border, and U.S. and Mexican law enforcement officials generally agree many of the firearms used to perpetrate crimes in Mexico are illicitly trafficked from the United States across the Southwest border. GAO was asked to examine (1) data on the types, sources, and users of these firearms; (2) key challenges confronting U.S. government efforts to combat illicit sales of firearms in the United States and stem the flow of them into Mexico; (3) challenges faced by U.S. agencies collaborating with Mexican authorities to combat the problem of illicit arms; and (4) the U.S. government's strategy for addressing the issue. GAO analyzed program information and firearms data and met with U.S. and Mexican officials on both sides of the border.

Washington, DC: U.S. Government Accountability Office, 2009. 83p.

By Topher McDougal, David A. Shirk, Robert Muggah and John H. Patterson

Mexico is experiencing a surge in gun-related violence since 2006. Yet Mexico does not manufacture small arms, light weapons or ammunition in sizeable quantity. Moreover, Mexico has some of the most restrictive gun legislation in the world. It is assumed that a considerable proportion of weapons in Mexico are illegal, most having been trafficked from the United States (U.S.). The volume of firearms sold in the United States and trafficked across the U.S.-Mexico border, however, is notoriously difficult to record. Previous attempts have involved multiplicative approximations based upon the quantity of arms confiscated at the border.

San Diego: Trans-Border Institute, University of San Diego; Rio de Janeiro, Brazil: Igarapé Institute, 2013. 31p.