Cy Walsh has pleaded not guilty by reason of mental incompetence to murdering his father, former Adelaide Crows coach Phil Walsh.

The 55-year-old died from multiple stab wounds at his Somerton Park home in July.

His wife, Meredith, was also taken to hospital and treated for a leg injury.

Their 26-year-old son was charged with murder and has been detained at the secure psychiatric facility James Nash House.

Walsh today appeared in Adelaide Magistrates Court through a video link and entered his plea through his lawyer.

Walsh did not speak during the hearing.

He was dressed in a green tracksuit, was clean shaven and his hair had been cut short and was slicked back.

He will be required to re-enter his plea in the Supreme Court during his arraignment hearing on February 1.

Independent psychiatric reports will then be tendered to the court to determine the issue of mental incompetence.

If the court finds a defendant not guilty by reason of mental incompetence, but finds the objective elements of the crime proved, it will then consider a limiting term of supervision or detainment under a mental health licence.

The Adelaide Magistrates Court heard some forensic evidence was still outstanding, including a drug test.

The court is yet to hear any of the allegations against Cy Walsh, who will turn 27 next week.