BRASILIA (Reuters) - Brazil’s top federal prosecutor said on Friday she would not hesitate to demand federal authorities take control of an investigation of the murder of a Rio de Janeiro city councilwoman if it appears local police were not aggressively pursuing the case.

Brazil's Prosecutor General Raquel Dodge reacts during an opening session of the Year of the Judiciary, at the Supreme Court in Brasilia, Brazil February 1, 2018. REUTERS/Ueslei Marcelino

Prosecutor General Raquel Dodge told reporters she hoped it would not be necessary for her to petition Brazil’s top appeals court to give federal police and prosecutors control over the investigation of the assassination of Marielle Franco, 38, a rising star in the Socialism and Liberty Party (PSOL).

Dodge has already taken the initial bureaucratic steps required to monitor the work of Rio de Janeiro state investigators’ efforts to find those responsible for the Wednesday night killing of Franco.

The councilwoman was shot four times in the head as she rode in the back of a car after attending a women’s empowerment event in Rio. Her driver was also killed, while a press secretary in the car suffered cuts but was not seriously hurt.

The federal government decreed a month ago that Brazil’s army would take over all security operations through the end of the year in Rio, where murders have risen sharply.

Franco, part of a commission overseeing the military intervention, harshly criticized the move on Sunday, saying it could worsen police violence against residents.

She also repeatedly criticized Rio’s police for the repeated killings of innocents in the city’s numerous shanty-towns who are often caught in the crossfire as drug gangs and officers engage in firefights in highly populated areas.

Federal police on Friday were investigating the origin of the 9 mm ammunition used in Franco’s killing.

A source with direct knowledge of the investigation told Reuters that the ammunition was originally part of a large lot purchased by the federal police in 2006.

The ammunition was apparently stolen and has been used in more than 50 crimes since, the source said on condition of anonymity, as they were not authorized to discuss the matter.