Video footage of the moment Ian Tomlinson was struck by a riot officer at the G20 protests guardian.co.uk

The police officer suspended following the death of Ian Tomlinson during G20 protests has been questioned on suspicion of manslaughter, after a second postmortem showed that the newspaper vendor did not die of a heart attack.

The Independent Police Complaints Commission said: "Following the initial results of the second postmortem, a Metropolitan police officer has been interviewed under caution for the offence of manslaughter as part of an ongoing inquiry into the death of Ian Tomlinson."

The new postmortem showed that Tomlinson died from an abdominal haemorrhage. The cause of Tomlinson's injury has not been established, but investigators will now have to decide whether alleged police assaults on the 47-year-old contributed to his death.

The dramatic shift in the Independent Police Complaints Commission's criminal inquiry into the alleged assaults came after the results of the second post mortem were revealed. Police previously said Tomlinson had died of a heart attack.

Tomlinson collapsed and died around 7:25pm on 1 April, shortly after being attacked by at least one riot officer. He had been attempting to walk home from work when he was confronted by lines of riot police.

An officer was suspended and a criminal inquiry launched after the Guardian revealed footage showing the attack on Tomlinson from behind.

Today the City of London coroners court released the following statement:

"On 9 April 2009 HM Coroner for the City of London opened and adjourned the inquest into the death of Ian Tomlinson. In so doing he received evidence of identification and the provisional findings and opinion as to the medical cause of death, from a report prepared by consultant forensic pathologist Dr F Patel, instructed by HM Coroner to conduct the post-mortem examination. The pathologist's final opinion must await the completion of additional tests.

"Dr F Patel made a number of findings of fact including descriptions of a number of injuries and of diseased organs including the heart and liver. He found a substantial amount of blood in the abdominal cavity. His provisional interpretation of his findings was that the cause of death was coronary artery disease.

"A subsequent post-mortem examination was conducted by another consultant forensic pathologist, Dr N Cary, instructed by the IPCC and by solicitors acting for the family of the late Mr Tomlinson.

"Dr Cary's opinion is that the cause of death was abdominal haemorrhage. The cause of the haemorrhage remains to be ascertained. 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.

"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.

"The IPCC's investigation into the death of Ian Tomlinson is ongoing."