Can Murder Be Tracked Like An Infectious Disease?

If I asked you to think of a murderer, what's the image that springs to mind?

If you're like most people, you'll probably think of an evil psychopath, or someone bent on revenge. Perhaps you'll see a criminal mastermind, who eliminates rivals on his way to riches. Or a strung-out drug addict, who kills because she needs money to get high.


"We think of individuals who commit homicide as being unlike the rest of us," said April Zeoli, a public health researcher at Michigan State University's School of Criminal Justice. "They are crazy, or substance users, or had a bad childhood. There is some reason specific to the individual that they are committing homicide."

Zeoli recently decided to test that theory using the lens of public health research: When scientists study the outbreak of an infectious disease like AIDS or the flu, they don't ask what it is about specific individuals that made them sick. They look for broader patterns, knowing that illness in any individual stems from a process of contagion.


"We looked at homicide as an infectious disease," Zeoli said in an interview. "To spread, an infectious disease needs three things: a source of the infection; a mode of transmission; and we need a susceptible population."



"We hypothesized that the distribution of this crime was not random, but that it moved in a process similar to an infectious disease, with firearms and gangs operating as the infectious agents," the researchers wrote in a paper they published in the journal Justice Quarterly.



Studying homicide via a broad public health lens, Zeoli added, also allowed researchers to identify positive outliers: "We actually had some areas within Newark that were resistant to homicide, despite being surrounded by areas with high homicide rates. So we need to investigate why those little islands exist."

To use the language of infectious disease research, Zeoli said, once researchers figure out what makes some neighborhoods "resistant" to homicide, despite having the same risk factors as areas with high homicide rates, policymakers could apply those insights to "inoculate" other areas in order to prevent homicide from spreading.


