Brazilian officials have said they do not believe there was a Scotland Yard cover-up over the shooting of Jean Charles de Menezes.
Richard Latham QC (left) and John Cummins leave the inquest
But ambassador Manoel Gomes Pereira said he had been "perplexed" by leaks from the inquiry that contradicted early police and eyewitness reports.
He "completely" trusted the Independent Police Complaints Commission, he added.
The IPCC has said it will end its probe this year. Mr Menezes died after being mistaken for a suspected bomber.
The 27-year-old electrician was killed at Stockwell Tube station, south London, a day after the failed 21 July bombings.
Mr Pereira was flanked at a news conference at the Brazilian Embassy on Tuesday by Wagner Goncalves, of Brazil's federal prosecutor's office, and Marcio Pereira Pinto Garcia, of its ministry of justice.
The men had travelled to the UK to look into the circumstances surrounding the shooting, and on Monday met Metropolitan Police Deputy Assistant Commissioner John Yates.
Mr Garcia said Mr Yates had told them "one hour after the incident [the police] sent a note to the IPCC - they were informed since the beginning".
According to Mr Yates the inquiry into the shooting had not been handed over for 72 hours because of the mistaken suspicion Mr Menezes was connected with terrorism, Mr Garcia said.
"From then on, all the evidence is with the IPCC," he said.
Documents leaked last week relating to the IPCC probe contradicted eyewitness reports and initial police quotes that Mr Menezes' "clothing and demeanour" added to suspicions he was a suspected suicide bomber.
Mr Pereira said: "We were perplexed - we were trying to find out some explanation for the new facts, for the new information leaked."
At a reopened inquest into the death on Tuesday, the IPCC said it would complete its inquiry by Christmas but not publish its report until possible criminal or disciplinary proceedings in the case were completed.
Richard Latham QC, representing the IPCC, told the hearing: "No-one would expect an investigation such as this to be hurried.
"It must be wide-ranging and conducted with very considerable care."
Coroner John Sampson also requested a progress report on the IPCC inquiry from senior investigator John Cummins.
Mr Cummins said a "comprehensive handover package" had been received from the Metropolitan Police on 27 July.
He added: "There is a considerable amount of fresh work to be done."
The inquest was then adjourned until 23 February.
Harriet Wistrich, a solicitor representing the Menezes family, afterwards repeated calls for a further public inquiry into the shooting.
She said there was "a whole load of misinformation that has been circulating for quite some time and that has not been put right".
A memorial Mass was held on Tuesday evening at St Anne's Church, east London, in Mr Menezes' memory.
Father Federico Ribeiro, of the Brazilian chaplaincy in Westminster Diocese, said before the service that Brazilians would be praying for justice.
He said: "We want to pray for our Brazilian friend who we had here many times. We want the truth to prevail to show he was innocent. Do not distort the truth. We love the police so please do not disappoint us and the whole population.
"We pray for them to be honest and the truth to prevail."
Newspaper reports say Tube staff have disputed police claims CCTV cameras were not working at Stockwell station, where Mr Menezes was killed last month.
Police removed recordings from the surveillance system immediately after the 22 July shooting but apparently found them blank, the reports said.
But Tube workers have reportedly told the IPCC that some cameras covering the relevant platform were working.
Mr Menezes was shot a day after the failed London bombings
The BBC had earlier been told the cameras' disks were removed the day before in the investigation into the 21 July failed bombings.
A Transport for London spokesman said it could not comment while it was co-operating with the ongoing IPCC inquiry.
Meanwhile, the sister of a woman killed in the 7 July attacks has said the row over Mr Menezes' death is undermining the fight against terrorism.
"We are hampering the police investigation by crucifying the police and the chief of police, who has been trying to do his job," said Dania Gorodi, of Mill Hill, north London.
"It was a tragic mistake what happened to this family but it was a mistake."
Her sister Mihaela Otto, 46, was killed in the Piccadilly Line blast near Russell Square.
Mrs Gorodi, 48, added: "We need to support the police now. It's the fight against terrorism that should be the focus."
Shadow minister for homeland security Patrick Mercer also called for support for the police.
"Nothing must distract the Metropolitan Police from preventing further attacks against the capital or indeed against other major cities in this country, " he told the ITV News channel.
But Mr Mercer criticised the lack of information given to him about the force's shoot-to-kill policy.
"I would have been extremely interested to know how the rules of engagement have changed, how they have been adapted," he added.