Megan Jayne Somerville given 15-year limiting term for stabbing her two children on side of Adelaide motorway

A mother of two who stabbed her sons on a busy Adelaide motorway has wept in court as she was sentenced.

Megan Jayne Somerville has been sentenced for stabbing her two sons in the middle of traffic on the North-South Motorway.

A mother who stabbed her two children on the side of a dark motorway in 2022 has told a court she accepts her need to be detained in a secure mental health facility and no longer wishes for community supervision.

Megan Jayne Somerville, 38, wiped tears from her face as Supreme Court Justice Sandi McDonald read her remarks and fixed a limiting term for her to remain in James Nash House for 12 years.

Her counsel, Jeff Powell, previously asked the court to consider releasing Somerville into the community on licence, but on Tuesday said that, after receipt of a secondary report, their position had changed.

Justice McDonald said Somerville’s treating psychiatrist was of the “compelling and considered” expert opinion she was not ready to be released and detention was the best option for her prognosis.

Somerville was sentenced to 15 years of a limiting term, inside a mental health facility.

“In my opinion it is too soon to commence (supervised leave) for Ms Somerville,” Justice McDonald quoted from the psychiatrist’s report.

“Ms Somerville has residual symptoms of psychosis that directly underpinned her index offences.”

On August 15, 2022, police were called to the North-South Motorway just before 11:30pm following reports a woman had been detained by a member of the public.

The court previously heard Somerville, of Modbury Heights, stopped her silver Honda sedan and removed her two sons, aged three and eight at the time, before stabbing them “a number of times” with a knife.

The court also heard she was under the effects of meth, cannabis and prescription medication that night.

A forensic psychiatrist who assessed her told the court Somerville’s recount of the incident included her fear she and her children were “facing a fate worse than death” and they were being groomed to kill her.

In March, Justice McDonald found the mother not guilty of attempted murder due to mental incompetence.

The court previously heard the father of her six-year-old son – who was just three when he was stabbed – describe the lengthy trauma the “heinous”, near-lethal attack had left on his family.

Through her lawyer, Somerville apologised to her sons, telling them she didn’t deserve their forgiveness – but hoped one day for it anyway.

Justice McDonald fixed a limiting term of 15 years, reduced to 12 to account for the time she had already spent receiving treatment in James Nash House.

A limiting term is a court-ordered period under mental health supervision, in a secure facility or the community, equal to the prison term an unaffected person may receive for a crime.

Justice McDonald said in “due course” Somerville would be able to apply to the Supreme Court for release on licence when “her risk to the community has been reduced to acceptable levels”.