Megan Jayne Somerville: Adelaide mum accused of repeatedly stabbing her kids in late-night attack on the North-South Motorway allegedly fuelled by drugs

A mother accused of stabbing her two young children was allegedly under the influence of a cocktail of methamphetamine, cannabis and prescription drugs at the time, a court has heard.

Megan Jayne Somerville, 37, appeared in Adelaide Supreme Court via video link from a secure mental health facility on Monday.

Somerville has been held at the facility since the alleged attempted murder of her sons, aged three and eight, on the city’s North-South Motorway on August 15, 2022.

Emergency services were called to the highway at around 11:30 p.m. after reports that Somerville had been pulled over by members of the public who had intervened.

Somerville allegedly pulled over her silver Honda sedan, took her children out of the car and stabbed them “multiple times.”

The boys were rushed to the Women’s and Children’s Hospital in Adelaide, where they underwent emergency surgery.

In December 2022, the Modbury Heights mother pleaded not guilty to two charges of attempted murder by reason of mental incapacity.

But last October, Judge Sandi McDonald heard that Somerville was unlikely to deny attacking her children, despite reports prepared by the defence which concluded she was mentally unfit at the time.

Somerville (pictured) allegedly stabbed her two sons multiple times on the side of a highway in 2022

Professor Jason White told the court on Monday that Somerville was believed to be a “frequent” or “daily drug user”.

Significant amounts of illegal and prescription drugs were found in her system both 85 minutes and 14 hours after the alleged stabbings, the court heard.

The tests showed that 0.39 mg of methylamphetamine was found per liter of blood. That means that the level at 23:30 may have been as high as 0.43 mg.

“Methylamphetamine was found in the blood sample, which is illegal in Australia. Amphetamine was also found, which is both a therapeutic and illegal drug,” Professor White told the court.

‘…Therapeutic concentrations (of the drug) are typically between 0.02 and 0.05, so (her results) were about ten times higher.’

‘THC, the main active ingredient in cannabis, was also found.’

Somerville (pictured) claims she should not be found guilty of attempted murder due to her poor mental health at the time of the alleged attack

Somerville (pictured) appeared in the Adelaide Supreme Court via video link from a locked mental health facility on Monday morning

Prescribed antipsychotic medications were also found.

Professor White believes the high levels of drugs found in Somerville’s system may have made her impulsive, confused, agitated, paranoid and obsessive.

He also concluded that the drugs could worsen an underlying mental health condition, such as schizophrenia.

The court also heard that a friend of Somerville had testified that he had “obtained” an “8-ball” of meth the night before the alleged attack.

Judge McDonald will hear more evidence later this week.