A Sydney Court has heard "vitally important" material relating to the case against former teacher Chris Dawson for the alleged murder of his wife 37 years ago may have been shredded.

Key points: The material involved interviews with witnesses and potential witness

The material involved interviews with witnesses and potential witness The court heard there was about 100 hours of material

The court heard there was about 100 hours of material Mr Dawson is next due in court on June 20

Mr Dawson's lawyer, Greg Walsh, told Sydney's Downing Centre Court the material believed to have been shredded was collected by journalist Hedley Thomas for The Teacher's Pet podcast.

Thomas investigated the 1982 disappearance of Mr Dawson's wife Lyn in an award-winning podcast by The Australian.

Mr Walsh told the court the material involved interviews with witnesses and potential witnesses.

Mr Dawson, 70, was in December charged with murdering Lyn, whose body has never been found.

He is on bail and was in court for today's hearing.

Outside court, Mr Walsh said he had been given a transcript of comments Thomas made at a public event in Brisbane.

"Mr Thomas made a representation that the material for chapter five of podcast seven must be shredded or 'otherwise we'll all go to jail'," he said.

Mr Walsh said if all the material collected by Thomas was not handed to police, it would be subpoenaed.

"We've got to get to the bottom of this … Chris Dawson's entitlement to a fair trial, in my respectful opinion, has been seriously prejudiced by the conduct of Mr Thomas and many others."

Later this evening, The Australian issued a media statement which said Mr Walsh had "distorted" the truth by making claims of document destruction.

"The exact words spoken by Mr Thomas were as follows: '[The lawyers] got back to me today and said 'we, ah, we think chapter five of episode seven needs to be significantly shredded, cut out,' and I was like 'oh, why'? And they said 'well, you'll go to jail if it stays'.'

"[Mr Walsh's comments] appear to have been made for the purpose of smearing the reputation of Mr Thomas," the statement read.

The Australian said they are continuing to respond to requests from prosecutors for documents relevant to Mr Dawson's trial and all downloads of the podcast had been suspended.

The court heard there was about 100 hours of material within the podcast.

Mr Walsh said if it was not provided to the defence it would be a "huge task" to keep to the timetable set down for hearing the case.

He said that Thomas would be called as a witness when the committal hearing begins.

Mr Dawson is next due in court on June 20.