Rio’s military police department said in an email to the BBC that four military officers who were in a patrol car had come under fire near the Carmen Cintra street by two armed men on two motorbikes. After a gunfight, they returned to the police station, unaware that people had been hit.

But investigating cases involving the police is not easy. Paulo Roberto Mello Cunha, a state prosecutor, leads a team that looks into allegations of police violence, but mostly there is not a lot it can do. “You have to count on the police to investigate the police,” he says. “I don’t do forensics, for example.”

States in Brazil have two separate police forces - the military force in charge of public order, and the civil force to carry out forensics and investigations.

Apart from the chronic lack of personnel and resources, Cunha’s team often struggles with inadequate evidence from crime scenes that have not been preserved, sometimes intentionally.

There are frequent claims from relatives and activists of people being taken to hospital already dead in alleged attempts by officers to cover up possible wrongdoing, or even of guns and drugs being put next to victims’ bodies as ways to incriminate them.

I was told that residents and Jean Rodrigo’s relatives had gathered next to his body to protect the area until the forensics team arrived. His family also quickly released his pay cheque from the federal government and his jiu-jitsu certificates, hoping it would demonstrate that he was a working man with no links with criminals.

Often, fearful witnesses remain silent and prosecutors reject taking on investigations, aware that they could become targets. Cunha himself has been given bodyguards after he and his family received threats. “We rarely have a proper investigation,” he says. “Sometimes it works. Depending on the stars, it’ll work. But that’s not the rule.”

Since 2016, when his group was set up, they have investigated some 1,300 cases. Charges have been pressed in less than 5% of them. “Before, we had 0% of the cases, so I think we’re building something,” he says. “The bar is pretty low.”

“I won’t backtrack,” Witzel said in August, arguing his government was “in the right way”. Proof of this, he said, was the drop in homicides - there were 2,392 cases in the state between January and July, a drop of 23% from 2018. Violent thefts and robberies are also falling, while the police have seized large amounts of drugs and weapons.

The Red Command - Rio’s largest drug gang, controlling a vast number of neighbourhoods - was even running out of ammunition, Witzel claimed. He also said that drug traffickers should be legally defined as terrorists, with harsher sentences. “You can’t combat terrorism with flowers,” he said last month. “The message has been sent: Don’t fight the police.”

It is not yet clear whether the improvements celebrated by Witzel are a direct result of his policies, experts say. The fall in the homicide rate, in particular, appears to follow a national trend - official numbers suggest 6,543 cases nationwide between January and February, a 20% drop on the same time last year.

While Witzel has focused on drug traffickers, critics say he has downplayed the threat from violent paramilitary groups created by policemen, active and retired, known as milícias. None of the deaths in police operations between January and June occurred in districts where they are active, according to UOL Notícias, a news website.

Witzel’s office did not respond to requests for an interview.

Outside Rio’s poorest districts, there is some support for Witzel’s policies, as frightened residents despair of seeing an end to the violence. “We have to kill those boys,” one resident of Barra da Tijuca, a fashionable seaside neighbourhood where President Bolsonaro has a private residence, tells me, referring to drug traffickers. When I say innocent people are also being killed, he replies: “It’s the price!”

The police were responsible for almost a third of all violent deaths - essentially any death that is not accidental or natural - in Rio de Janeiro between January and July, according to the state’s Institute for Public Safety.

Parliamentarian Renata Souza says there is “widespread fear” that extrajudicial executions are being carried out. “There are operations in which the killings are indiscriminate... These are massacres committed by the state.”

In February, residents of Fallet-Fogueteiro in the centre of Rio said nine men were tortured and stabbed by officers in a house, killed even after they had surrendered. Police said the suspects had responded with gunfire when they arrived, and the residence reportedly had 182 bullet holes on it.

Locals, however, said the police had surrounded the place and that there had been no gunfight. In total, 15 people were killed, the deadliest raid in Rio in 12 years. Witzel defended the operation as “legitimate”.

In May’s operation with the helicopter in Maré, police said they were looking for a suspected drug lord. Pictures of pupils fleeing a school as the police hovered overhead went viral. Eight people were killed in the raid, four of them in a single house.

Again, residents said the men had already surrendered when they were killed. A witness, whose house was broken into by the heavily armed suspected drug traffickers, told me on condition of anonymity: “One of [the suspects] said ‘Perdi’, ‘I’ve lost it.’ The policeman said: ‘You didn’t only lose. My order is to kill.’”

Both cases are still being investigated by the police. But Jurema Werneck, executive director of Amnesty International Brasil, says authorities are allowing this “violent approach” by officers.

“Killing people can’t be considered public policy,” Werneck, who was herself born in a favela, says. “We have the proper way to deal with [suspected criminals]. It has to be in front of justice and not in front of guns.”