The bullets used to kill Marielle Franco, a human rights activist and Rio de Janeiro city councilor, came from lots that had been sold to Brazil's Federal Police in 2006, Rio television station RJTV reported Friday, citing forensic experts.
The tests conducted Thursday indicated that that police force purchased the bullets from a Brazilian company, CBC, on Dec. 29, 2006, and that the batch numbers were 220-821 and 220-822, the station added.
The 38-year-old Franco, an Afro-Brazilian, LGBT woman from one of Rio's most crime-ridden "favelas" (shantytowns) who had denounced police brutality and extra-judicial killings and was a staunch critic of military interventions in Rio's slums, was gunned down in a drive-by shooting while riding in her vehicle in downtown Rio on Wednesday night.
The driver of the car also was killed, while a press officer who was riding in the back seat sustained injuries but survived the attack.
Franco, who was the fifth-highest vote-getter in Rio de Janeiro city council elections in 2016 and had participated in a political rally just hours before her death, was buried Thursday at the Caju cemetery in downtown Rio.
The councilor's death shocked Brazilians, tens of thousands of whom took to the streets Thursday to mourn her death and demand justice during emotional, nationwide tributes.
The crime occurred nearly a month after Brazilian President Michel Temer issued a decree putting the military in charge of security in Rio de Janeiro state, a move aimed at combating a wave of violence there that dates back to the 2016 Olympics and left 6,731 people dead last year.
Some 100 police officers have been among those killed, while 10 children have died after being struck by stray bullets.
In a statement Thursday, London-based human rights group Amnesty International denounced the "targeted assassination" and said it was "a sickening development" that must be fully, promptly and impartially investigated.