RIO DE JANEIRO — Brazil’s federal police arrested the men Sunday suspected of ordering the killing of a Rio de Janeiro councilwoman in 2018, a long-awaited step after years of society clamoring for justice.

The brutal assassination of Marielle Franco, a 38-year-old Black, bisexual Rio de Janeiro city councilwoman in a drive-by shooting, shook Brazil profoundly and reverberated across the world.

Two federal police sources with knowledge of the investigation told The Associated Press that congressman Chiquinho Brazão and his brother Domingos Brazão, a member of Rio state’s accounts watchdog, were detained on suspicion of ordering the hit against Franco. Both have alleged connections to criminal groups, known as militias, that illegally charge residents for various services, including protection.

The sources didn’t make clear what their suspected motive was.

On Wednesday, Brazil’s Justice Minister Ricardo Lewandowski said the country’s Supreme Court had validated a plea bargain for the shooter who was arrested along with the driver in 2019.

The investigation into Franco’s murder had been troubled for years. Rio’s state civil police couldn’t break the case after the arrest and indictment of the shooter and the driver. The lead detectives were changed four times until February 2023, when federal authorities took control.

The driver admitted in 2023 to the double murder of Franco and her driver. The shooter, disgraced former police officer Ronnie Lessa, signed a plea bargain deal with authorities in January, and his admission led to Sunday’s arrests.

Rivaldo Barbosa, the head of Rio’s police when the murder took place, was also arrested for alleged obstruction of the investigation, the sources said.

Franco worked as an assistant to then-state lawmaker Marcelo Freixo in 2008 as he presided over a special committee investigating militias in Rio’s state assembly. Freixo’s final report indicted 226 suspected militia members and politicians and government employees, including Domingos Brazão.

While Brazão was mentioned in the report, he wasn’t indicted.

Political violence isn’t uncommon in Rio, and such killings are often linked to territorial and political disputes. But they typically go unsolved and never elicit the same level of outcry as Franco’s death did. She had been a rising political star, making her name by exposing police abuse and violence against residents of working-class neighborhoods known as favelas.

Franco, known by her first name, grew up in a favela, the Mare neighborhood near Rio’s international airport. She became a human rights activist there after her friend was killed by a stray bullet in a shootout between police and drug traffickers. She worked for Freixo, investigating organized crime, then went on to win a seat in Rio’s city council in 2016.

She stood out as one of the only Black women on the council and, while her assertiveness and mere presence ruffled some, she remained unbowed.

On the evening of March 14, 2018, Franco left an event to empower young Black women when a car pulled up alongside hers and opened fire. She and her driver, Anderson Gomes, were killed on-site.

The brutality of the slaying and the political hope she had embodied transformed her into a symbol of left-wing resistance in Brazil and abroad. People staged massive protests to channel their outrage; her silhouette was painted on walls across Brazil.

Her sister, Anielle Franco, has been appointed Brazil’s minister of racial equality.

Anielle Franco said Sunday on social media that the arrests gave an answer “to favela residents who voted for Marielle Franco, for women who put their bodies at the service of politics.”