Published in Scientific Reports, 2020.
Homicide is one of Mexico’s most critical security challenges, with violence escalating sharply after the war on drugs was declared in 2007. The Monterrey metropolitan area (MMA), a major business hub in northeastern Mexico, became one of the most emblematic conflict zones, suffering hundreds to thousands of casualties over the following years.
In this work, we propose a network-based approach to describe how homicidal violence evolved and spread through the city over an eight-year period. We define a homicide network where nodes represent geographical entities—municipalities and neighborhoods—connected through spatial and temporal relationships. By constructing yearly co-occurrence networks, correlating neighborhoods where homicides occurred within the same week, we uncover key structural patterns:
- At the municipal level, homicide correlations decrease with distance, consistent with spatial diffusion of violence.
- At the neighborhood level, however, correlations are not distance-dependent: the highest co-occurrences appear between distant neighborhoods and a central polygon in downtown Monterrey.
- A disproportionate number of homicides occur near the 85th freeway, which connects the MMA to the US border.
- Socioeconomic barriers delineate the boundaries of homicidal violence, and the relationship between crime and the urban landscape—particularly highways—evolves over the cartel-related years and the period that follows.
This network approach provides a spatiotemporal description of how violence clusters, spreads, and interacts with the built environment in a metropolitan area.