Violence is a part of life in this slum on the outskirts of Rio de Janeiro. Shootings are common and death squads of former and off-duty police officers, funded by local businessmen, are known to knock off undesirables.

But even by the brutal standards of Nova Iguacu (search), last week's massacre of 30 people apparently by a band of rogue policemen was shocking, starting with the severed head thrown over the gate of a police station.

"It's beyond shocking really," said Tim Cahill, a researcher from the London office of the human rights group Amnesty International (search) who arrived to investigate the slayings. "It just shows how cheap human life has become."

And yet the March 31 bloodbath failed to create much of a stir in Rio, partly because it was eclipsed by the pope's death — Brazil is predominantly Roman Catholic — and partly because people are accustomed to bad news coming out of trash-strewn slums like Nova Iguacu, which is in the poor, gritty Baixada Fluminense section of the city, a full 20 miles away from Rio's picturesque beaches.

"Without a doubt, the news of the death of the pope took on such vast proportions that this horrible fact was somewhat forgotten," said Rev. Luciano Bergamin, bishop of Nova Iguacu. "We have to forget the death of the pope a little and make sure these facts don't repeat themselves."

So-called police death squads have been operating with impunity in Baixada for 25 years, locals and human rights groups say.

"Everybody knows death squads operate here, most people even know the names of the people associated with them," Lindbergh Farias, mayor of Nova Iguacu, said in a radio interview following the killings.

So far, 12 current or former police officers have been arrested and eight of them have been charged with murder. Four allegedly did the shooting; the others provided backup.

According to State Security Secretary Marcelo Itagiba, they were upset over the arrest of eight fellow officers caught on video dumping the bodies of two men, both suspected criminals, outside a police station and throwing the head of one decapitated victim over the gate.

The first shots were fired at a sidewalk bar, killing nine people, including several shirtless teens left lying in a pool of blood around a video game machine. Most of the victims were shot in the head and chest at relatively close range, medical examiners said.

The killers next chased two men who ran across the street down a dead end alley and finished them off there.

Then they picked off two men riding bicycles on their way to the neighboring town of Queimados, where they killed 12 more people in two different spots, apparently at random.

"The first incident didn't really surprise me. That's the kind of thing death squads do," said Inacio Cano, who teaches at the Laboratory for Violence Analysis at Rio de Janeiro's Federal University. "But for them to imagine they could kill 30 people and get away with it. They must have killed so many people over the years that they lost track of scale."

Just miles away, in Rio's wealthier suburbs, residents seemed largely unconcerned about the tragedy, reflecting the deep divide between the rich and poor.

Few affluent residents ever set foot in the mostly black community of Baixada, where the murder rate is about 50 percent higher than the state average. Residents endure three-hour bus and train rides to work at low-paying jobs on Rio's upscale south side.

Two police massacres in 1993 — the Candelaria massacre (search), in which police killed eight people when they opened fire on at least 40 street children sleeping in front of a cathedral, and the Vigario Geral massacre that left 21 people dead — generated far more attention because they occurred in downtown Rio.

Rio Mayor Cesar Maia said he didn't believe the brutality would harm the city's image or have any impact on its hosting of the 2007 Pan American Games because they were unprecedented and "because there is no reasonable expectation they will be repeated."

"The barbarous crimes cause indignation and revulsion but they don't create a sense of everyday risk," Maia told the Associated Press.

Among the victims was 19-year-old Jonas Lima da Silva, who had popped out to get some cigarettes and never came home. Standing over his grave, Silva's grief-stricken mother seemed to say that poverty was to blame.

"If this was a middle-class kid, I wouldn't be here," wailed his mother, Rosa Maria da Silva. "If this were the governor's son, they would have already caught the killers."