A Rio councilwoman’s killing was a mystery. An arrest gave a peek at corruption keeping it unsolved

Two days after Rio de Janeiro city councilwoman Marielle Franco's 2018 assassination, her widow sat down with the chief of the state's civil police, Rivaldo Barbosa, who pledged to do everything in his power to hold the guilty parties to account. Federal Police arrested Barbosa on March 24 — over six years later — for allegedly helping orchestrate Franco’s killing and taking money to obstruct the very investigation he would oversee.