The family of a newspaper seller who died of a heart attack minutes after being caught up in G20 protest clashes said today they were "hopeful" action would be taken against any police officer whose wrongdoing contributed to his death.
Speaking on behalf of relatives, Paul King said it had been painful to watch footage of the "violent assault" on his stepfather, Ian Tomlinson.
"Ian was a much loved and warm-hearted man and we are still coming to terms with his sudden death under such tragic circumstances," he said.
"The developments of the past week, particularly the footage showing Ian suffering a violent assault from police, have been painful for us to take in.
"We are hopeful that the IPCC (Independent Police Complaints Commission) will fulfil their duty to carry out a full investigation into his death and that action will be taken against any police officer who contributed to his death through misconduct."
Mr Tomlinson died of an apparent heart attack as thousands of protesters converged on the City of London nine days ago.
Video footage later emerged of the 47-year-old being shoved to the ground by a policeman shortly before his death.
The officer pictured has been suspended and the IPCC, the police watchdog, is investigating.
Mr King, 26, of east London, was speaking before a memorial march by protesters walking through London to lay flowers at the site of Mr Tomlinson's death.
Hundreds dressed in black and bearing banners gathered at Bethnal Green police station to march in silence to the Bank of England.
Relatives did not join the protesters, but Mr King told them: "We thank you for remembering Ian today.
"We ask all of you here today to honour Ian's memory by making it a peaceful and respectful march."
He added: "We may have a long and difficult process ahead of us in getting justice and hope we can rely on your continued support in the future."
As people gathered outside the police station to join the march, the atmosphere was charged but remained non-violent.
David Mellows, who took part in the G20 protests, harangued police officers posted outside the station over their colleagues' behaviour during clashes.
"The only violence I witnessed that day was police violence," he said.
"It was a miracle no one else was killed."
Also present was Chris Knight, one of the organisers of the protest outside the Bank of England earlier this month.
The professor was previously suspended by the University of East London after he warned bankers could be "hanging from lampposts".
He said today: "Ian Tomlinson seems to have been killed by the forces of law and order.
"I have seen the video - maybe they didn't - but they (police) have some explaining to do.
"There was no violence from our side."
Some protesters taking part in the march have suggested they could remain in the City until tomorrow.
A notice on the G20 Meltdown website, maintained by those associated with last week's demonstration in the City of London, said: "The question is, will people feel like just going home, meek and mild, after laying flowers?
"Some of us may feel strongly like staying at that place until Ian Tomlinson and his family get justice. Will there ever be such a chance again to turn the world upside down?"
Mark Barrett, a supporter of the march and an organiser of the G20 Meltdown, said: "The point of coming together is to commemorate that something terrible has happened.
"Our hearts are with the friends and family of Ian Tomlinson and we can't possibly imagine what it must feel like for them.
"We want there to be a really wide, open inquiry into the whole issue of police tactics and to open it up ever wider to get the voices heard so that something like this can never happen again."