(CNN) Two arrests in Brazil may shed light on the killing of a popular young politician, whose death sparked national protests one year ago.

On Tuesday, former Rio de Janeiro police officers Ronnie Lessa and Elcio Vieira de Queiroz were arrested in connection with the killing of city councilwoman Marielle Franco and her driver, the Rio de Janeiro state government announced.

Franco was killed in a drive-by shooting in Rio's Estacio neighborhood on March 14, 2018. Her driver, Anderson Pedro Gomes, was also killed, and a press secretary who worked for Franco was injured.

According to the state's press release, Queiroz drove the vehicle that pulled up alongside Franco's car. Lessa is accused of pulling the trigger. The accusations of their involvement bolster long-held suspicions that Franco, 38, was assassinated for her activism against police violence and killings in poor Rio neighborhoods.

Lessa is a retired military police officer. Queiroz, also a former officer, was expelled from the force in 2011, a spokesperson told CNN.

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