Ian Tomlinson's son, Paul, and his widow, Julia, talk to Paul Lewis guardian.co.uk

The police officer who attacked Ian Tomlinson at the G20 protests in London in 2009 could be prosecuted for manslaughter after an inquest jury ruled that the newspaper seller was unlawfully killed.

Returning their verdict after three hours of deliberation, jurors said Tomlinson died of internal bleeding in the abdomen after being struck with a baton and pushed to the ground by a police officer.

For legal reasons, the verdict did not name the officer, Metropolitan police constable Simon Harwood.

However, the jury said that "excessive and unreasonable" force was used when he struck the newspaper vendor who "posed no threat".

The director of public prosecutions, Keir Starmer, immediately said he would "review" his decision last July not year not to prosecute Harwood.

There were shouts of "yes" from Tomlinson's family when the jury confirmed their belief that the 47-year-old father of nine was unlawfully killed.

The family's lawyer, Jules Carey, said : "Today's decision is a huge relief to Mr Tomlinson's family. To many, today's verdict will seem like a statement of the blindingly obvious. However, this fails to take account of the significant and many obstacles faced by the family over the last two years to get to this decision."

Police initially denied Tomlinson had contact with police officers before his death on 1 April 2009.

The Independent Police Complaints Commission only launched a criminal inquiry a week later, after the Guardian released video footage showing Tomlinson being struck from behind by Harwood near the Royal Exchange Buildings.

The footage was played repeatedly during the five-week hearing at the International Dispute Resolution Centre in Fleet Street, London.

Jurors were given two divergent explanations of his death.

The first pathologist to conduct a postmortem examination on Tomlinson, Dr Freddy Patel, said he died of a heart attack as a result of coronary heart disease. He was contradicted by three other pathologists who examined the body, all of whom found he died of internal bleeding in the abdomen.

Starmer said last July that complications with the medical evidence led him to believe prosecutors would be unlikely to prove a cause of death.

His decision, which was backed by the attorney general, Dominic Grieve, prompted widespread anger and questions in parliament.

The Metropolitan police commissioner, Sir Paul Stephenson, said he could understand the "outrage" over the decision not to prosecute Harwood.

Jurors at the inquest were told they could only decide Tomlinson was unlawfully killed if they were convinced beyond reasonable doubt, the same burden of proof which would apply in a criminal trial.

The Crown Prosecution Service will now also consider new medical evidence given to the inquest by Professor Kevin Channer, a heart expert who contradicted the theory that Tomlinson died of a heart attack.

He said defibrillator readings of Tomlinson's heart activity obtained moments after his collapse were "entirely inconsistent" with Patel's explanation of his death.

Tomlinson had been trying to walk home from work through the demonstrations near the Bank of England on the evening he died. An alcoholic, he had been drinking heavily and was looking vacant and confused as he was repeatedly turned away from police cordons.

At 7.20pm, he stumbled on to Royal Exchange Buildings, a passage police had been ordered to clear. Tomlinson had his hands in his pockets and was walking away from police when he was struck with a baton and pushed from behind by Harwood.

During three days of evidence at the inquest, Harwood, 43, told jurors that he believed at the time that Tomlinson was obstructing police and he believed his actions were proportionate.

Harwood will face a Metropolitan police gross misconduct hearing at which he stands accused of "inadvertently causing or contributing to" Tomlinson's death. If found guilty by the disciplinary panel, Harwood, who is currently suspended on full pay, would almost certainly be sacked.

The verdict brings to an end a two-year wait for Tomlinson's family, who maintain police attempted to cover up officers' involvement in his death.