Two police officers attended the newspaper's Fyshwick office yesterday afternoon, and seized items belonging to journalist Noel Towell which they believe could be evidence in relation to the investigation.

Detective Superintendent Chris Sheehan and Sergeant Allison Williams left with Towell's digital recorder and notebook.

Towell, who is the newspaper's legal affairs reporter, had recorded and transcribed an interview about the matter with Mr Cahill last week.

The interview was published in full in The Canberra Times on Thursday, November 5.

When asked the reasons for the search warrant being executed, Superintendent Sheehan said, ''We're investigating an allegation against a very senior public servant and that's about as far as I can go today.''

The search warrant stipulated that anything in relation to the investigation, including notes, files, emails and recording devices, could be seized.

The police officers needed to have reasonable grounds for suspecting that the items searched would afford evidence as to the commission of the offence that Mr Cahill ''attempted to pervert the course of justice contrary to sections 44 and 713 of the ACT Criminal Code'' in relation to the case.

The Canberra Times broke the story last week that Mr Cahill had come under scrutiny for his actions in allegedly providing materials to a visiting magistrate in relation to an upcoming case.

The search warrant follows news this week that Mr Cahill has been stood down from the bench pending a Judicial Commission into his conduct.

The ACT's Attorney-General, Simon Corbell, told the Legislative Assembly on Tuesday a complaint had been made ''that, on or about 21st of October, 2009, the Chief Magistrate caused or procured the creation and transmission of written material to Special Magistrate Peter Lauritsen which had, or might have had, the effect of interfering with the conduct of criminal proceedings to be heard by him relating to a public figure known professionally and socially to the Chief Magistrate before the proceedings commenced''.

The commission is separate to the police investigation, sparked when Director of Public Prosecutions Jon White called in police last month over material provided to the Victorian Magistrate, Mr Lauritsen.

Mr Lauritsen had been in Canberra to preside over a two-day hearing.

Details of the case cannot be published for legal reasons, but prosecutors aborted the court proceedings after the Melbourne magistrate revealed that he had been sent a detailed background briefing on the case.

The DPP has alleged that a bundle of documents had been sent by email to the visiting magistrate including the case against the accused, matters for consideration in the hearing, relevant case law and a copy of the existing suppression order preventing the media from reporting details in the case.

The Chief Magistrate, who is due to retire on December 15 after a 34-year career on the magistrates' bench, confirmed last week that ACT Policing detectives had executed a search warrant on his chambers on November 2, a move he described as unnecessary.

Mr Corbell announced his decision to hold the Judicial Commission the first of its kind for an ACT judicial officer in the Assembly on Tuesday, saying he was acting on a complaint about Mr Cahill's conduct made by his fellow magistrates John Burns and Karen Fryar.

He said he had taken advice from the ACT Government solicitor before referring the matter to the DPP. ''Whilst any possible criminal charges are currently being investigated by the AFP, I am still bound to acknowledge the gravity of the alleged behaviour,'' he said.

Mr Cahill issued a statement on Tuesday maintaining that preparing written material for a visiting magistrate to assist in hearing a matter was not uncommon, and said he was looking forward to being exonerated by the Judicial Commission.