A SOUTH Australian man charged with the murder of his twin brother has been found not guilty by reason of mental incompetence.

Lucas Brian Timothy Cawte shot his brother Jake on a property at Willunga, south of Adelaide, in March last year.

In the South Australian Supreme Court on Thursday, Justice Kevin Nicholson ruled Cawte was not mentally competent when he committed the offence. He described the incident as “tragic”.

Previously, a court heard Cawte shot his brother twice to stop him “going to God”, and intended to take his own life but instead handed himself into police.

Prosecutors last week told the court that a toxicology report had been obtained and the Director had now conceded Cawte was “not mentally competent to commit the offences”, The Advertiser reports.

Counsel for Cawte said his treating psychologist had listed him as “very stable” at the moment and he would seek limited supervised leave from James Nash House as part of his licence conditions.

The family had three sons and a daughter, and were well-known and liked in the tight-knit community and throughout the famed wine region, according to The Advertiser. Travel movies posted on YouTube by the brothers show the pair happily enjoying trips to Indonesia and other parts of Asia, where they playfully interacted with each other and with local people

Jake had occasionally made news as a young boy growing up in Willunga, which was known for slate mining after its establishment in 1839 but has increasingly become a food and wine tourism hub.

As a 12-year-old in 2005, Jake and a handful of local youths made the news when the future of a skateboard park under construction at Willunga became embroiled in a legal stoush.