The first autopsy of the victim, Ian Tomlinson, 47, concluded that he suffered a fatal heart attack. But a second found the cause of death to be internal bleeding, The Daily Mail reported.
A constable with the Metropolitan Police has been questioned "under caution," suggesting that he is likely to face a criminal charge, officials said. The constable was captured on videotape apparently knocking Tomlinson to the ground.
Jules Carey, the Tomlinson family's solicitor, said the past week has been difficult for the family because they were aware of the autopsy findings but could not discuss them for fear of prejudicing the police investigation of the death.
"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 was violently assaulted by a police officer and died from internal bleeding," said Paul King, Tomlinson's stepson. "As time goes on we hope that the full truth about how Ian died will be made known."