A host of criminologists joined the high brass of the Chicago Police Department last Friday at the downtown offices of an influential University think tank, where they discussed strategies for securing a safer Chicago against its soaring homicide rate.

The University’s Crime Lab, a policy group established in 2008 that has helped the city evaluate the effectiveness of its crime-fighting initiatives, convened the symposium. Panelists pointed out the wider social impact of the city’s unsettling criminal trends.

“Victims are not the only victims,” said Jans Ludwig, director of the Crime Lab. “Social science research suggests that every homicide that occurs in a city reduces its population by 70 people.”

Frank Zimring, a professor of criminology at the University of California, Berkeley, presented his own research on the “miraculous” turnaround New York City experienced between 1990 and 2009, which he attributes to specific changes in policing strategies, not changes in the city’s population or institutions.

“There are huge changes in policing that take place in New York: more cops—40 percent more cops in the 1990s—different tactics…and policing got a lot more aggressive on the street,” he said.

Importantly, Zimring said, the city did not have to rely on mass incarceration, and New York’s rate of imprisonment actually fell during the 1990s by 28 percent; the country as a whole saw a 65 percent jump in its rate of incarceration during the same time, even though it only saw half as steep a decrease in crime.

CPD Superintendent Garry McCarthy, who spent several years in the New York Police Department in the 2000s, spoke to the unique challenges of policing Chicago, where the vast majority of murders are by gunshot.

“In NYC at the the midway point of 2011, they had seized 1,185 firearms by arrest,” McCarthy said. “At that same time, Chicago, a city with one-third the population, one-third the landmass, one-third the police department had seized 4,422; that’s seven guns per capita for every one that NYC seizes.”

As it seeks to clamp down on firearms in Chicago, the CPD will have to shore up its efforts by building trust and strengthening community institution to keep progress from backsliding, McCarthy explained.

“It’s not chasing kids off the corner; it’s explaining to people why they’re stopped, why we’re working here, why we’re doing the things that we’re doing,” he said.