Detective Chief Superintendent Joanne Shanahan, 55, and Tania McNeill, 53, were killed in a three-car collision in April 2020 when Harrison Kitt drove through a red light in Adelaide at high speed.
He pleaded not guilty to two counts of causing death by dangerous driving and one count of causing harm and was found not guilty because of mental incompetence.
Prosecutors conceded he was suffering a psychotic episode at the time of the crash.
Kitt will not serve jail time but be subject to mental health supervision while living in the community, with the District Court on Tuesday setting that period, known as a limiting term, at 10 years.
In a previous hearing, David Edwardson QC, for Kitt, said his client was deeply remorseful for the incident and offered his apologies to the families.
While in a statement, Kitt's mother Kathy said the family understood the ruling on his mental health would prompt mixed community reactions.
"Some will find it difficult to understand that what occurred can be explained by mental illness," she said.
"We only wish that we had understood some of the warning signs in Harry's behaviour."
But in a victim impact statement, Supt Shanahan's sister Georgie Steiner said Kitt should not ask for forgiveness.
"Don't ask for our forgiveness. Don't allow anyone else to ask for forgiveness. This is not possible," she said.
