Supreme Court judge Lex Lasry has decided with "considerable regret" to shift from Wangaratta to Melbourne the trial of Ian Thomas, accused of the murders in the north-eastern Victorian town.

Justice Lasry said conditions at the Wangaratta police station cells were not suitable to hold Mr Thomas during what was expected to be a four-week trial.

Justice Lasry's main concerns were that Mr Thomas would be unable to have contact visits with his legal team if being held in one of the station's two cells, he would have to share a cell, and he would not have access to a computer.

The judge said he was of the view that the trial should have been held in Wangaratta given that was where the alleged offences had taken place but it was important for Mr Thomas to get a fair trial where he could contribute to his legal defence.

The trial was set down to begin on August 3.

Mr Thomas, 35, of Balga, Western Australia, has been charged with murdering his parents, Bill, 64, and Pauline, 63, who had been married for 40 years and had five children, on April 22, 2013, at their Great Alpine Road home.

Mr Thomas's legal team had initially pushed to have the trial held in Melbourne claiming the Thomas family was so well-known in the district, having been there for more than 160 years, that it would be hard to find impartial jurors but Justice Lasry rejected this claim.

A committal hearing held in 2014 in the Wangaratta Magistrates Court was told Mr Thomas had allegedly confessed to the killings to his married lover, Jacinta Emselle, a day after the murders.

"He said his mum came out to the shed and she was being really awful and she had pushed him too far, so he told me he put his hands around her neck and just squeezed," Ms Emselle said.

She said Mr Thomas told her he then went to the house and lay waiting for his father, Bill, to come home. He allegedly shot him in his chest before hitting him in the head with a blunt object. Mr Thomas then allegedly placed his  parents' bodies side by side on doonas on the lounge-room floor.

Police arrested Mr Thomas in Meredith, between Ballarat and Geelong, following the discovery of his parents' bodies.