By Ian Dunt
The Independent Police Complaints Commission (IPCC) has announced an independent investigation into the death Ian Tomlinson at the G20 protests last week.
The commission also announced it intends to conduct a second post-mortem on Mr Tomlinson's body.
Demands for an investigation became all-encompassing after a video emerged of him being struck by police minutes before his heart attack.
The IPCC had previously limited its investigation to managing an inquiry undertaken by the City of London police, rather than launching its own.
The decision to turn this into a full independent investigation might suggest the IPCC does not have full confidence in the City of London police's inquiries.
"As with all our investigations, the level of our involvement remains under constant review and when new evidence comes to light, we will always reassess," an IPCC spokesperson said.
The video, which was handed in to the Guardian, appears to contradict early police reports which said he died of natural causes.
Both the police and the home secretary sounded a sympathetic note today.
Commissioner Sir Paul Stephenson said: "The images that have now been released raise obvious concerns and it is absolutely right and proper that there is a full investigation into this matter, which the Met will fully support."
Home secretary Jacqui Smith appeared open to a further investigation, saying: "If it [the IPCC] identifies - and I understand people's concern - the need for a criminal investigation, that also needs to be pursued."
The IPCC already confirmed the current inquiry is a criminal investigation and that the commission will liase with the Crown Prosecution Service (CPS).
A Metropolitan police spokesman said: "It would not be appropriate to comment while an IPCC investigation is ongoing."
The video shows Mr Tomlinson walking home from work as a newspaper vendor when a policeman behind him appears to strike his legs with a baton.
He is then thrown to the ground, before remonstrating with police from the floor. Minutes later he has a heart attack and dies.
"At the moment the investigation is focused on identifying the officers in the footage," said IPCC deputy chair Deborah Glass.
"Several have already come forward and all efforts are being made to trace those who haven't."
The footage was filmed by a New York fund manager who was attending the demonstration out of interest.
Shadow home secretary Chris Grayling said: "These latest revelations are extremely alarming and leave big questions to be answered by the police.
"It's right that there should be an independent investigation. The inquiry must be completed quickly so that any further appropriate action can be taken."
Lib Dem justice spokesman David Howarth was furious. "This video clearly shows an unprovoked attack by a police officer on a passer-by. It is sickening," he said.
"There must be a full-scale criminal investigation. The officer concerned and the other officers shown in the video must immediately come forward."
An IPCC spokeswoman said: "We are now attempting to recover this evidence.
"We will be assessing this along with the other statements and photographs that have already been submitted."
Although the footage implies Mr Tomlinson died from police actions, there is still a chance his heart attack was unconnected to his contact with the police.
Other aspects of the police statement released on the day of the protest - April 1st - are not substantiated by the videos, photographs or eyewitness reports handed in to the Guardian or the IPCC.
Police said they were pelted by bottles as they tried to give medical assistance to Mr Tomlinson, but that account has not been corroborated by evidence, although one bottle is clearly thrown.
Green party home affairs spokesperson and London Assembly member Jenny Jones has called for any police found to have behaved violently at the protest to be suspended.
"The police's primary objective at all times should be to maintain community safety," she said.
"Their management of the G20 protests clearly failed in this respect. Any officer involved in needlessly violent actions should be identified and suspended from public order policing pending the outcome of ongoing inquiries."