The distraught parents stood outside the yellow police tape for three hours, begging and pleading to be let in so they could see if it was indeed their son lying dead in the cold, dark Chicago alley.

Finally, the tape lifted and they were escorted to the 17-year-old boy's blood-soaked body.

"They did not let me hold my child," Kimberly King-Hopkins said as she wiped a steady stream of tears from her eyes.

"After they showed me him lying there on the ground, with his eyes up, I couldn't touch him," she recalled. "I couldn't just grab him and hold him. They wanted me to identify him ... then we had to walk away because it's a criminal investigation."

Just a few miles from President Barack Obama's luxurious house are neighborhoods bereft of hope where small children are hit by stray bullets walking home from school and the elderly are afraid to step outside.

Homicide rates -- which in Chicago's worst neighborhoods are 10 to 40 times the national average -- only tell part of the story.

The Chicago police logged more than 9,400 incidents of "public violence" this year: those are homicides, rapes, robberies and assaults that involve guns, happen in public places like the street or city parks, and aren't classified as domestic violence.

A dozen of the city's 77 neighborhoods averaged at least one incident a day and accounted for nearly half of the year's total.

Pastor Corey Brooks decided to do something about it after hoodlums shot at mourners walking into his church last month to pay their respects to King-Hopkins' son, Carlton.

It was the 10th funeral he'd presided over for a young black man shot dead on Chicago's South Side in less than a year.

Brooks preached with such passion during the funeral that four young men handed over the guns they had carried into the sanctuary of New Beginnings Church on Martin Luther King Drive.

Then he announced a 21-day fast to protest the violence and camped out on the roof of an abandoned fleabag motel across the road to draw attention to the cause.

"In the middle of a wonderful city you have this desert where people are really struggling and the violence is outrageous," he said as he sat in the rooftop tent on a recent chilly day.

"So we have to take a stand against it and do something because, if we don't, it's never going to change and lives are never going to be better."

Two weeks into the fast, he came down for a few hours after another young man -- who turned out to be one of Carlton's best friends - was gunned down and Brooks was called to the hospital to comfort the family.

"I never will forget how that looked to see a young, 16-year-old boy with his mouth open, with his eyes still open and his body in a white bag zipped up to his neck," Brooks said.

"No mother, no family should ever have the pain of burying their son that way or seeing their son killed that way."

Brooks dug in and decided he would not leave the roof again until he'd raised enough money to buy the motel and turn it into a community center, something his Woodland neighborhood is sorely lacking.

Some 31 days into his vigil, an anonymous donor offered to match any donations up to $50,000 that were made over Christmas.

The donations poured in, including ê50 from a man in prison who said that if he'd has something like Brooks' Project Hood growing up "I probably wouldn't be here."

Brooks has raised ê193,261 so far, including the matching grant. He has another $250,000 to go.

The roots of the violence run deep. People here blame poverty, drugs, gangs, dysfunctional families, bad schools, bad values, a lack of opportunity, a lack of resources, easy access to guns.

But at some point, the violence becomes the root of the problem, said epidemiologist Gary Slutkin, whose Ceasefire program has expanded from Chicago to 15 US cities, London, Iraq, South Africa and Kenya.

The shooting has to stop before people feel safe walking on the street, shops and businesses can reopen and kids can concentrate at school because they're not suffering from stress disorders, Slutkin said.

When violence is the social norm, even the best parents can't counteract the pressure of life in the hood.

"Instead of looking at this as a problem of people that are bad, we're looking at this as behavior that's modeled and copied," Slutkin told AFP.

"Kids want to do what the other kids are doing -- they join the pack. That's how evolution has set us up."

King-Hopkins and her husband are solid, church-going people who keep a spotless home and do their part for the community by running a drug rehabilitation center.

They still haven't come to grips with how a good kid -- a kid everybody seemed to like, a kid who had 1,000 people turn out for his funeral -- could have ended up in that alley.

Carlton cared too much about being cool, his father said. He wouldn't stop hanging around with the wrong kind of kids, his mother said. But mostly, he just lived in the wrong neighborhood.

"He was shot down just because," Daryl Hopkins said.

"The more police officers investigate, the more they talk on Facebook, the more we find out stuff, it was just out of pure hate."