The study was led by April Zeoli, an assistant professor in the School of Criminal Justice at Michigan State University. Zeoli and her team studied homicide rates in Newark, NJ between 1982 and 2008 by entering the time and location of each murder into software typically used to monitor infectious disease. They found that the program could be used to predict and model the spread of homicides in a manner similar to the movement of infectious diseases throughout a population.
In the 26 year period encompassed within the study, the homicide rate in Newark was on average three times higher than the national average. The homicide 'epidemic' originated from central Newark after a rise in homicide cases in that area before spreading to the southern and eastern wards of the city. As a number of homicide cases cropped up in the areas outside of central Newark, homicide rates in central Newark dropped. This pattern was maintained as homicide cases spread throughout the city, with rises in homicides spreading to neighboring 'susceptible' areas before dwindling back down at the source. Zeoli hypothesized that gangs and firearms acted as the infectious agents which were the vehicle for the spread of homicides throughout Newark.
Certain areas of the city, however, remained unaffected throughout the 26 year period, similar to the resistance observed in certain populations when tracking the spread of infectious diseases. By studying these areas, Zeoli suggests, law enforcement officials may be able to identify the variables which confer 'resistance' to a given population and devise ways to encourage similar qualities in at-risk population. Identifying vulnerable populations- typically in poor, low-income areas- which the homicide 'epidemic' is most likely to spread to next may also serve as a useful tool for law enforcement officials to predict the spread of homicides and intervene when possible by directing their resources to those areas.