The link between the president’s son and a death squad

The Rio das Pedras militia was created midway through the year 2000. At the time, these groups were seen as a positive thing—an answer from citizens to fill a void left by the state in gang-dominated favelas. As reporter Raphael Tsavkko Garcia explained last year in his article “How armed militias became part of Rio’s everyday life,” these groups were a kind of security patrol unit acting against drug traffickers. They were made up of police officers, firefighters, and prison guards. Even the authorities supported them.

Two decades later, it is safe to say that most Brazilians have changed their minds on militias. They have proven to be as deadly and oppressive as the gangs from which they were supposed to free citizens. Militias started by “offering” protection to residents of a community. With time, they branched out to new forms of funding.

They monopolize services such as illegal cable TV, internet, furniture, transportation, water, and gas. Nothing is sold without their blessing—and without giving them a cut of the profits. Most have also controlled land within their areas of influence, employing a rarely seen kind of ruthlessness. And some, such as the Rio das Pedras militia, have gone even deeper, creating their own army of guns for hire. From Rio’s oldest militia sprouted “The Office of Crime,” arguably the deadliest and most secretive death squad in Rio de Janeiro.

Comprising former and current military police officers, “The Office” is known for its...