On a scorching Saturday in late July, Mayor Rahm Emanuel and Police Superintendent Garry McCarthy joined a march against violence in Austin, partly to publicize the City Council’s new and more stringent curfews for children 16 and younger. Channel 5 led its 5 PM newscast with the march and even found time to report on a rally held that same day by CeaseFire, a local organization dedicated to halting the cycle of killing in high-risk communities. But Tio Hardiman, director of the organization’s “violence interrupters” program, wasn’t even identified onscreen, nor did the reporter mention the victims of area shootings that occurred before and after the mayor’s march. By the time of the 10 PM newscast, any mention of CeaseFire had been dropped altogether.

CeaseFire’s relative anonymity may end with The Interrupters, a stirring new documentary that opens Friday for a two-week run at Gene Siskel Film Center. Producers Steve James (director of Hoop Dreams) and Alex Kotlowitz (author of the 1991 best seller There Are No Children Here) are longtime friends, but this is their first professional collaboration, inspired by a May 2008 story on CeaseFire that Kotlowitz published in the New York Times Magazine. Gary Slutkin, an epidemiologist in the School of Public Health at the University of Illinois-Chicago, spent a decade in Africa fighting cholera, tuberculosis, and HIV/AIDS before returning to the U.S. and founding the Chicago Project for Violence Prevention, the parent organization of CeaseFire. Slutkin’s central insight has been to approach street violence like an infectious disease, one that can be treated by identifying the source of outbreak and intervening before the infection spreads. For him there are no good or bad people, just healthy or unhealthy people; violence is unhealthy behavior, but behavior can be changed.

In the film James and Kotlowitz chronicle a year in the lives of three former criminals—Eddie Bocanegra, Ameena Matthews, and Ricardo “Cobe” Williams—who now work for CeaseFire as violence interrupters. Through their close community ties they target individuals at risk of committing murder (over drugs, turf disputes, other murders, or simply perceived slights) and intervene before the rage spirals out of control. At a time when 52 million Americans lack health insurance and seek medical treatment through pharmacy-chain clinics or hospital emergency wards, poor blacks and Latinos from the inner city are often underserved. When Bocanegra, Matthews, and Williams intervene in neighborhood crises, they function like old-fashioned doctors making house calls, though they arrive not with pills or vaccines but with techniques that draw on cognitive behavioral therapy. They come with the talking cure.

Matthews is the daughter of Jeff Fort, the imprisoned leader of the El Rukns street gang, and she used to relish her lifestyle as a gangland enforcer. “Drugs, guns, party, fun,” she recalls, “that was it.” One day she was shot, and while in recovery she turned down her father’s offer of revenge, an episode she regards as her first mediation. Now she roams Englewood, chatting up residents and defusing the sort of verbal battles that escalate into deadly violence. “The story about sticks and stones will break your bones, but words can never hurt you?” she says. “Words’ll get you killed.” Early in The Interrupters she intervenes in an altercation right outside her office, ushering into her car a furious young man who’s been hit by a rock and driving him to his cousin’s house, where cooler heads prevail. By finding a comical aspect to the situation, Matthews further lowers his stress level.

Prior to his work for CeaseFire, Williams served 12 years for drug trafficking and attempted murder. Gregarious and seemingly unflappable, he enjoys a high success rate with his clients, partly because of his work ethic; he’s so dedicated that when CeaseFire was forced to lay him off during one of its periodic funding droughts, he put in the hours anyway. The level of trust he inspires pays off for James and Kotlowitz. At one point a 32-year-old man, aptly nicknamed Flamo, informs Williams, whom he met in jail, that he intends to gun down a police informant who instigated a raid on his home. When Williams and fellow violence interrupter Rodney “Hot Rod” Phillips arrive on Flamo’s doorstep, he’s in no mood to be pacified, but they manage to avert a confrontation through the simple expedient of taking him out to lunch so he can blow off steam.

Like many of these interrupters, Bocanegra is a former high-ranking gang member who wants to atone for his own violent acts. He served 14 years for murder and still seems haunted by his crime. Now he works with gang-affiliated residents of South Lawndale, but he also takes a special interest in young children terrified by the carnage. Many schools are reluctant to admit they have problems with violence, so Bocanegra has devised his own entrée into classrooms: teaching art. Along with the lesson, students receive an open invitation to talk about whatever worries them.

On Wednesdays these three interrupters meet at the School of Public Health to confer with Hardiman, discuss their caseload progress, and identify new threats. “[T]he Wednesday meetings are a kind of therapy,” Kotlowitz wrote in his New York Times Magazine piece. “One staff member laughingly compared it to a 12-step program.” In the movie one interrupter scans the room and calculates that, with all the prison terms served, they’ve accumulated 500 years of wisdom. Sometimes potential offenders are invited to these meetings as part of the confrontation process that’s used to resolve conflicts. The interrupters are trained to listen for the sort of assumptions that grow from distorted perceptions, which in turn can be fed by the mercurial and not always reliable word on the street.

The stakes are high: a recurrent image of The Interrupters is the memorial sites for slain young men, strewn with flowers and teddy bears. On a wall in Altgeld Gardens, inscribed with names of the dead, a handwritten scrawl announces, “I am next.” One heartbreaking sequence, shot at a funeral home in Greater Grand Crossing, documents the wake for “Duke” Smith, a teenager killed in retaliation for a shooting incident. Matthews attends at the request of the victim’s mother, who’s heard that more reprisals will follow at the wake, and the event is permeated by a gangsta vibe: one kid poses for a photo alongside the open casket as though he’s being snapped with a celebrity. “Last year, of the 125 homicides where we serviced those families, about 90 percent were young people,” reports funeral director Spencer Leak. “These children don’t expect to live past 30.”

CeaseFire’s techniques often work: a 2008 study conducted by Northwestern University’s Institute for Policy Research showed that, while shootings or attempted shootings had declined across the city, the drop was much steeper in the areas where CeaseFire operates. That same study reported that 99 percent of CeaseFire clients attested to the organization’s positive impact on their lives, including help in finding employment and completing school. But changing deeply ingrained behavior can be a gradual process, and prone to setbacks. In one case, when Matthews tries to help an angry 18-year-old woman, talking about her feelings stirs up such negative emotions that she violates her parole and winds up back in jail. When the interrupters do succeed, the results can be riveting: in one scene a 17-year-old ex-con returns to the beauty salon he held up three years earlier and tries to make amends with the owner and staff. His visit has a cathartic effect on one woman, her tears and recrimination giving way to forgiveness and, incredibly, an embrace for the former thief. In this little corner of a community, at least, the wounds have begun to heal.