The masked policeman caught on film hitting and pushing a man who later died at the G20 protests has been questioned on suspicion of manslaughter.

The Metropolitan Police officer was interviewed under caution earlier this week after a second post-mortem examination concluded that Ian Tomlinson died of severe internal bleeding — contradicting an earlier finding that he had had a heart attack.

Video footage and photographs showed Mr Tomlinson, who was not a protester, being harassed by police dogs, struck by a masked officer and shoved to the ground minutes before he collapsed and died on April 1.

The Independent Police Complaints Commission, which is investigating his death, said: “Following the initial result of the second post-mortem a Metropolitan Police officer has been interviewed under caution for the offence of manslaughter.” The officer, a constable in the Territorial Support Group who has been suspended from duty, attended the interview voluntarily and has not been arrested.

Scotland Yard is under intense scrutiny with four reviews or inquiries into G20 policing and two officers suspended from duty for alleged police brutality that was caught on film. In the immediate aftermath of Mr Tomlinson’s death, police said that medically trained officers who tried to help him were pelted with bottles by protesters. The IPCC is in the spotlight after saying initially that Mr Tomlinson had had no contact with officers before his death, and leaving the conduct of the initial investigation to police.

But, as in the case of Jean Charles de Menezes, the Brazilian engineer who was mistakenly shot dead by police in July 2005, the full story of how Mr Tomlinson died is emerging bit by bit and calling into question the accuracy of official accounts.

The second post-mortem examination was carried out by Dr Nat Cary, one of the country’s leading forensic pathologists, over a week ago at the request of Mr Tomlinson’s family. The IPCC asked that details were withheld until it had interviewed the officer.

The family was concerned that the first examination was carried out by Dr Freddy Patel. He had previously been disciplined by the General Medical Council for passing sensitive information to journalists about Roger Sylvester, who died in police custody in 1999. He was given a reprimand that did not affect his fitness to practise.

The City of London coroner’s court said yesterday that Dr Patel had found Mr Tomlinson had “a number of injuries” and a diseased heart and liver. He found a large amount of blood in the abdominal cavity but concluded that cause of death was heart disease.

Dr Cary’s provisional finding was that Mr Tomlinson died from an “abdominal haemorrhage”, the cause of which was yet to be determined. The coroner’s court said: “Dr Cary accepts that there is evidence of coronary atherosclerosis but states that in his opinion its nature and extent is unlikely to have contributed to the cause of death.” It added: “The opinions of both consultant pathologists are provisional and both agree that their final opinions must await the outcome of further investigations and tests. These are likely to take some time.”

Paul King, Mr Tomlinson’s stepson, said after the second results: “First we were told that there had been no contact with the police, then we were told that he died of a heart attack; now we know that he died from internal bleeding.” An inquest has been opened and adjourned but a full hearing will not take place until the IPCC investigation, a possible prosecution and any potential appeals are completed.

Scotland Yard said it was co-operating fully and proactively with the inquiry. A spokesman added: “The Metropolitan Police Service wishes to reiterate its sincere regret in relation to the death of Ian Tomlinson.”

Boris Johnson, the Mayor of London and chairman of the Metropolitan Police Authority, said people around the country had been deeply disturbed by the circumstances of Mr Tomlinson’s death. “There must now be a fast and transparent conclusion to the IPCC investigation,” he said. “The Met receives and deserves the overwhelming support of the people of London, but the family of Ian Tomlinson need answers.”

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