SA dad denies killing three-year-old son

An Adelaide landscaper detained in a mental health unit had pleaded not guilty to murdering his three-year-old son.

David Janzow, 37, entered his plea on Friday, via video link from James Nash House to the Adelaide magistrates court.

He denied murdering his son, whose name is suppressed, on July 8 last year.

His lawyer, Stephen Ey, said he would ask the Supreme Court to investigate his client's mental condition at the time of the boy's death.

Soon after Janzow's wife rang police on July 8 expressing concerns for his welfare and that of their son, he drove up to an unrelated crash scene saying the boy was injured.

The boy was found in the car with injuries consistent with being repeatedly stabbed.

Janzow will face the Supreme Court on April 13.