Amnesty International (AI) [advocacy website] called for a full investigation [press release] on Thursday into the killing of Rio de Janeiro councilwoman Marielle Franco.

Franco, a 38-year-old human rights defender known for her outspokenness against police brutality, was shot dead late Wednesday night in what appears to be a targeted assassination. AI’s Brazil director, Jurema Werneck, cited the shooting as “yet another example of the dangers that human rights defenders face in Brazil” and stated that the “Brazilian authorities must ensure a prompt, thorough and impartial investigation into this tragic killing.”

Franco’s death comes just weeks after she was appointed rapporteur for a special commission that the city council created to monitor the government’s use of the military to take control of all public security through the end of the year in Rio. An expert on police violence [Guardian report], Franco was critical of the police and their alleged killings of innocent victims during interactions with drug gangs. Some sources have pointed to her denunciation of the police as a possible motive [Reuters report] for her murder.

In addition to being an activist against police violence, Franco was also known for her social work and for fighting for the rights of black women and youth as well as other marginalized communities. She won the fifth highest vote count when she was elected in 2016 and was in her first term in office.