The Tribune also has a map of homicides this year in Chicago, which shows how concentrated are most of the killings.
A few months ago, The Truth About Guns had linked to this article at Chicago Magazine on the distribution of gun violence within Chicago. A study was conducted of shootings (rather than just homicides) in general and links between the people involved. The reasoning for broadening the pool beyond homicides was that the researchers believed that death from a gunshot wound had a certain amount of fortuity that was not present in the case of looking at all shootings. Not surprisingly, the researchers discovered that a relatively small population was responsible for most of the violence. The key point from the article:
Papachristos constructs a social network—not a virtual one in the Facebook sense, but a real one of social connections between people—by looking at arrestees who have been arrested together. That turns out to be a lot of people in raw numbers, almost 170,000 people with a “co-offending tie” to one another, with an average age of 25.7 years, 78.6 percent male and 69.5 percent black. It’s also a large percentage of all the individuals arrested: 40 percent of all the individuals arrested during that period.
Within the entire group, the largest component of that whole co-offender group has 107,740 people.
Within the timeframe—from 2006 to 2010—70 percent of all shootings in Chicago, or about 7,500 out of over 10,000, are contained within all the co-offending networks. And 89 percent of those shootings are within the largest component.
Or, to put another way: the rate of gunshot victimization (nonfatal + fatal) in Chicago is 62.1 per 100k. Within a co-offending network, it’s 740.5—more than 10 times higher.It is interesting to compare this to another story from about a year ago which noted that the vast majority of homicides in Chicago were related to drug gangs:
“This finding has (at least) two implications for our understanding of non-fatal gunshot injuries,” the authors write. “First, the concentration of non-fatal gunshot injuries in networks such as these demonstrate that such incidents are more concentrated than previously thought, and even more concentrated than gun homicide by either demographic group or place. Our findings indicate that70 percent of all non-fatal shootings occur in networks comprising less than 6 percent of Chicago’s total population. This distribution of shootings within co-offending networks fundamentally changes how we assess the distribution of risk in Chicago.” (Emphasis theirs.)
Fewer than 2,000 utterly ruthless, well-armed bad guys may be causing a majority of Chicago's homicides. They're shooting and killing each other, motivated in part by profits from illegal drug sales, according to a veteran criminologist who has worked closely with the Chicago Police Department.
When they began rounding up 41 leaders of a notorious gang last week that allegedly grossed $11 million a year running open-air heroin and cocaine markets on the West Side, it was hailed as a law enforcement landmark, the first use of a new Illinois law designed to target a small cadre of the most violent criminals.
"There's probably 1,500 to 2,000 that are in a network of individuals that are continuously interacting in a negative way and at risk of shooting someone or being shot themselves," Professor Dennis P. Rosenbaum says.
Though he sometimes speaks like the UIC college professor he is, Dennis Rosenbaum has worked closely with the Chicago Police to understand the city's bloody-minded drug gangs. Rising to rule a gang requires an utter ruthlessness, emulated by the wannabe's in gang-dominated neighborhoods, especially in warmer weather when more residents are outside, watching.
"The smallest things can set this off," Rosenbaum says. "People can be disrespectful of someone else's girlfriend, because all these kids have going is their street credibility. And they will fight and die for that."