They're seldom mentioned by officials and are almost never identified, but paramilitary groups are increasingly embedded in Rio de Janeiro – and, with the slaying of a prominent politician in recent months, are ever more brazen.
When Marielle Franco, an outspoken activist for the rights of poor blacks in Rio's violence-plagued favelas, was gunned down, the most unusual thing was that authorities firmly pointed the finger at the paramilitaries, or "militias" as they're known locally.
Murders happen all the time in Rio de Janeiro state. There were 15 homicides a day in the first two months of the year, according to the Public Security Institute.
But with the focus nearly always on the drug gangs controlling swathes of the favelas, killings by militias – shadowy groups of ex-police and serving officers gone rogue – mostly pass under the radar.
Franco's killing, which was conducted in a chillingly professional manner, changed that. Franco had made a name for herself criticising what she said were police death squads in the favelas and now, in a deliberate and public way, she had been silenced.
"What they did to Marielle showed that what's happening in Rio is very serious," said leftist legislator Marcelo Freixo, who oversaw a congressional committee, joined by Franco, seeking to lift the lid on militia activities.
And six weeks after the killing, police have yet to make any arrests – more proof, critics say, of the militias' heavy hand.
Ironically, when the militias first formed around the year 2000, they were seen as an attempt to save Brazil's second biggest city from the ravages of drug gangs.
Uniformed police were unable to cope, and so vigilantes with close links to the police stepped in. The city authorities did nothing to stop them, seeing the loosely organized groups as far preferable to the dreaded narcos.
But like an out-of-control Frankenstein monster, the militias gradually morphed from neighbourhood protection into mafia-like protection rackets, using their muscle and expertise not only to fight drug gangs but to replace them as rulers of the local streets.
And from the streets, the militias have extended their influence into politics, all the while preventing the Brazilian media from daring to dig too far into their activities.
Their ranks are filled with current and former members of the police, firefighters, prison staff and soldiers, who tout their mission as "bringing morals and cleaning out the drug dealers," said sociologist Thais Duarte, an expert on the phenomenon.
Look back far enough, and you can trace the origins of today's militias to the underground death squads doing dirty work for the dictatorship between 1964 and 1985, said José Claudio Souza Alves at the Federal Rural University of Rio de Janeiro.
But today their principal role has veered into the commercial, making them more like mafia gangs than anything else.
In their strongholds of western Rio they control distribution of cooking gas, the Internet, cable television and local transport. In this way, a single militia group can earn an estimated US$7 million a month, experts say.
And because of their law enforcement links they are rarely brought to justice. They are "deeply rooted in the state apparatus," Duarte said.
"Militias have a different political and social capital to the traffickers," she added. "Traffickers have those negative stereotypes of being normally black and from favelas, while the militias are better off, they're white and older. All this gives them legitimacy."
The militias' protection rackets extend into politics, and they're not afraid to back up their threats.
"The militias sell votes in whole areas. They can offer a candidate control if he pays them and agrees not to get in their way," Alves explained.
But that's not all: "They have campaigned themselves, and once they are in office they are able to get total control," he said.
Those ambitions broke into the open in 2016 municipal elections when more than a dozen candidates were murdered, including one known as "Falcon," who also served as president of one of Rio's famed samba schools.
Whether Franco's murder will change anything for the militias remains to be seen.
As far back as 2008, they were blamed for kidnapping and torturing journalists from O Dia newspaper, a case that prompted a major investigation and arrests of some leaders. However, the paramilitaries overall continue to flourish.
"The only way to fight the militias is to attack their economic base," Souza said.