Abstract The relationship between poverty/social vulnerability and urban violence has been subject of numerous studies in Brazil. However, a seemingly contradictory phenomenon occurred for this explanation: there was an improvement in several social indicators in the period 2000-2010, but the incidence of homicides, a key indicator of violent crime, has increased. Given this, it is valid to suppose that, in addition to poverty/social vulnerability, other factors interfere in the occurrence of homicides. This study suggests the hypothesis that drug trafficking is one such factor. To do this, it carries out a case study on the city of Belem (Brazil), which begins by the investigation of the geographical distribution of the average homicide rates for the period 2013-2015 in the neighborhoods located in the continental area of the city. It then develops a statistical analysis of the same data based on the comparison of two linear regression models, one with only variables related to poverty/social vulnerability; and another that, besides these variables, adds the number of drug trafficking occurrences. The results showed that the second model had better explanatory power than the first one. This corroborates the hypothesis that drug trafficking is a contributing factor to the increased incidence of homicides.