A man accused of murdering his twin brother at their family's home south of Adelaide has been found not guilty by reason of mental incompetence.
The court previously heard Lucas Brian Timothy Cawte, 25, fatally shot his brother Jake in March last year on their family's property at Willunga.
He then drove to the Christies Beach Police Station and turned himself in.
Today, in South Australia's Supreme Court, Justice Kevin Nicholson found Cawte not guilty of murder by reason of mental incompetence.
"I am satisfied that at the time of the unlawful killing Mr Cawte was not mentally competent to commit the offence of murder," he said.
Cawte remains in James Nash House where he has been detained since his arrest.
His counsel last week told the court he was in a "very stable" condition in a rehabilitation ward.
Previously, Cawte's family had described the twins as "best friends".
Mr Cawte's lawyer entered a plea of not guilty on his client's behalf in September last year.
Last Friday, prosecutors told the Supreme Court they had conceded that the defendant had not been "mentally competent" at the time of his brother's alleged murder.
"I can indicate the director concedes that Mr Cawte was not mentally competent to commit the offences," prosecutors told the court.
Cawte will be ordered to serve a lifetime psychiatric supervision order, the conditions of which will be set at a later date.
