Victorian 'unintentionally' pleaded guilty to murder

A Victorian who pleaded guilty to killing his neighbour then gunning down both his victim's parents will argue short-term memory loss and dementia caused him to unintentionally admit the first murder.

Ian Francis Jamieson, 65, will argue he didn't mean to plead guilty to murdering Greg Holmes, 48, who he stabbed in Wedderburn in central Victorian in October 2014 before killing his neigbour's parents too, a court has heard on Thursday.

Jamieson will apply to have his guilty plea on the first murder charge set aside at a hearing before Victorian Supreme Court Justice Elizabeth Hollingworth next month, though no application will be made to change the guilty pleas on the second and third murder charges, the court heard.