Can a national approach to crime prevention sustainably reduce homicides? The present study examines the effectiveness of Mexico’s National Crime Prevention Programme (PRONAPRED) and United States Agency for International Development (USAID) funding in reducing the number of homicides. Analysing state-level data from 1990 to 2020, we find that PRONAPRED spending correlates with a reduction of approximately 12 homicides per state annually, although these effects were unsustainable over time. Our results highlight a significant inverse relationship between labour market participation and homicides, suggesting that policies promoting employment could effectively mitigate violence. Unlike PRONAPRED, USAID programme spending showed no statistically significant impact. We employed fixed-effects regression, a method that accounts for regional variations in homicide rates, to examine the impact of economic factors, including labour market participation. We also addressed methodological challenges, such as autocorrelation and endogeneity, through robust statistical techniques. Our findings contribute to the discourse on the efficacy of large-scale crime prevention programmes, providing insights into their limitations and potential areas for improvement in future policy design.