The family of Ian Tomlinson has made a fresh complaint to the Independent Police Complaints Commission about a police "cover-up" following his death.
Mr Tomlinson, 47, died after he was apparently pushed to the ground by a police officer during G20 protests in London on 1 April.
His stepson Paul King, 26, has raised a series of examples which he claims show the public were misled after the death.
A Metropolitan Police spokesman said they were unable to comment.
One officer has already been questioned on suspicion of manslaughter.
The family made a complaint about the death after video footage emerged of him apparently being knocked to the floor.
Mr King said: "The first statement from the police was that they were trying to save Ian's life while protesters were throwing missiles at them.
"Then the police liaison officer told us Ian died of 'natural causes'.
"After the video came out, the City of London investigator told us that it may have been a protester in disguise who assaulted Ian.
"Now it has come to light that a senior officer in the Metropolitan Police has given the investigation misleading information."
He added: "We are asking the IPCC for a full report on what looks like a cover-up."
The Tomlinson family solicitor said he hoped charges would be brought over the incident "sooner rather than later".
The IPCC have confirmed they are investigating information released to the media by police after Mr Tomlinson's death.
His family will hold a candlelit vigil on Tuesday night off Threadneedle Street in the City, where he collapsed.
Mr Tomlinson was a newspaper seller who was walking home past the protests when he was allegedly struck by the officer.
Two post-mortem examinations found the 47-year-old's death may have been due to a heart attack or abdominal bleeding.