Video of police assault on Ian Tomlinson, who died at G20 protest guardian.co.uk

The Metropolitan police learned today that one of its officers could face prosecution for the manslaughter of Ian Tomlinson at the G20 demonstrations.

The officer, a member of the Met's Territorial Support Group (TSG), struck Tomlinson with a baton and shoved him to the ground moments before he died.

Announcing that it had completed its criminal inquiry into the newspaper vendor's death, the Independent Police Complaints Commission (IPCC) said it had handed a file to the Crown Prosecution Service (CPS).

Senior lawyers from the Special Crime Division of the CPS will now consider the evidence provided by the IPCC to decide whether to prosecute the officer, and if so, on what charges.

The IPCC questioned the officer under caution for manslaughter in April. The officer came forward after the Guardian broadcast footage of him striking Tomlinson with a baton and shoving him to the ground at the 1 April protests.

In determining whether he should face trial, CPS lawyers will consider the footage, along with other documents and witness statements. The nature of the case means the director of public prosecutions, Keir Starmer QC, will be involved in deciding whether charges should be brought.

His lawyers are bound by a two-test rule requiring a "realistic prospect of conviction" in a prosecution that is deemed to be in the public interest.

In the event that the CPS successfully prosecutes the officer for Tomlinson's killing, he would become the first British police officer ever to be convicted for manslaughter for actions while on duty. The maximum penalty is life imprisonment.

In a statement, the IPCC said the investigation had been one of the largest it had ever undertaken and had been "the subject of huge public scrutiny". More than 40 IPCC investigators and other members of staff from all five regional offices were involved in the case, it said.

"We have had a remarkable response from the public and I would like to thank those people who have contacted us for all their help," said Deborah Glass, the IPCC commissioner for London.

Tomlinson's widow, Julia, said: "It has been a very difficult four months since Ian died and it is a relief to see some progress. The last information that the coroner put out was Dr Cary's view that Ian died from internal bleeding.

"Video footage made it clear to us, and everyone else, that Ian was the victim of an unprovoked assault by a police officer. If there is going to be any justice then it must be left for a jury to decide if the police officer is guilty of killing Ian. I hope the CPS will get the case in front of a jury as soon as possible. We would like to thank everyone who came forward as witnesses."

Glass said most of the video evidence passed to the CPS was collected by members of the public on cameras or mobile phones.

"Over 190 premises were visited during a CCTV trawl. This resulted in footage being obtained from more than 220 cameras. In addition, police footage has been reviewed, including that taken from police evidence gatherers and the police helicopter, as well as footage from people's mobile phones and cameras. This amounted to over 1,200 hours of footage, which has been reviewed by a dedicated team of IPCC investigators."

Statements were taken from 193 members of the public, as well as police officers and staff, and medical experts.

The 47-year-old Tomlinson had been trying to walk home from work past police cordons around the Bank of England when he was attacked on Royal Exchange Buildings, a pedestrianised passage, at about 7.20pm on 1 April. The officer's badge numbers were covered and his face concealed beneath a balaclava.

Tomlinson had his hands in his pockets and his back to the officer when he was attacked. No police officer went to his aid, and it was left to a bystander to lift him to his feet. He stumbled around 100 metres down Cornhill, clutching his side, before collapsing a second time.

The officer is understood to have faced allegations of aggression earlier in his career, after becoming involved in a road rage incident while off duty. The Met's vetting procedures are said to have failed to notice that the officer had an unresolved disciplinary matter.

Tomlinson's death led to widespread criticism of police brutality at the G20 demonstrations. Two parliamentary inquiries and a national review of policing by the official policing inspectorate have criticised the Met for tactics used against what were largely peaceful protesters in the City of London. The IPCC has received an additional 277 complaints about policing of the demonstration.

Police initially led Tomlinson's wife and nine children to believe he died of a heart attack after being caught up in the demonstration. In statements to the press, police claimed attempts by police to save his life by resuscitation were impeded by protesters.

The IPCC did not launch its criminal inquiry until six days after Tomlinson's death, when the Guardian gave the watchdog a dossier of evidence, including video footage and witness statements, that contradicted the police version of events.

Before then, City of London police were allowed to run the inquiry with some supervision from IPCC investigators. After watching the video of the attack, a senior City of London investigator told the family Tomlinson's assailant could be a member of the public "dressed in police uniform".

The IPCC is still conducting a second inquiry into whether the Met and City of London police misled the public over his death.

An early postmortem examination concluded that Tomlinson died of a heart attack. Police released a statement that he "died of natural causes" on the way home from work, but failed to mention the numerous injuries the pathologist found on his body, including bruises, lacerations and large amounts of blood in his stomach.

A second examination concluded that Tomlinson did of internal bleeding in the stomach, discrediting the first, which was conducted by a forensic pathologist who has since been suspended from an accredited government register of experts pending two investigations into his conduct.

The IPCC said it had asked the CPS to consider charges against a suspended TSG sergeant who is accused of assaulting two women in the space of 24 hours. The sergeant was caught on film striking one of the women, Nicola Fisher, at a memorial vigil for Tomlinson.