RIO DE JANEIRO — The question hangs heavily over this city: “Who killed Marielle Franco?”

It is raised in graffiti in virtually every neighborhood, emblazoned on T-shirts and written across banners displayed defiantly at mass demonstrations.

This week, just days before the anniversary of her killing, prosecutors provided a partial answer, charging two former police officers with carrying out the killing. The case’s main questions — including who ordered the killing and why — remain unanswered.

A year after her execution-style killing, the call for justice for Ms. Franco — a black, gay, feminist Rio de Janeiro city councilmember who was raised poor — has morphed into a rallying cry in a deeply-polarized nation for those who felt represented by her.

Her name and image have become an antithesis to the dominant political forces in Brazil as the right-wing president, Jair Bolsonaro, settles into office.