Two teenagers accused of planning to attack a South Australian high school with guns and explosives will face a Supreme Court trial after pleading not guilty to conspiring to murder.
The pair, aged 17 and 19, appeared before Adelaide Magistrates Court on Thursday over the plan, which is alleged to have targeted a school in the Riverland region.
During the brief hearing, magistrate Elizabeth Sheppard ruled the younger of the two boys had a case to answer, despite his lawyer's earlier claims the case was just "attention-seeking behaviour" from two youths acting tough.
Ms Sheppard ruled the boy "does pose an appreciable risk to the community", and should therefore be tried as an adult on the conspiracy to murder charge.
The teenagers are each facing one count of conspiracy to commit murder, which carries a maximum sentence of life imprisonment, among other charges.
They were arrested in November last year after police were alerted to the alleged plot.
The court has previously heard the pair persuaded each other to commit mass murder and they intended to kill as many people as possible in the attack.
Prosecutor Jim Pearce said at an earlier hearing it was the Crown case that the crime of conspiracy was committed "the minute you've got the meeting of minds".
He said the youths had experimented with crude explosives, including Molotov cocktails and napalm-style incendiary devices, and that the pair had three or four conversations about shooting up a school.
They were also "obsessed" with the infamous Columbine school massacre and other mass shootings in the United States, the court heard last month.
However, counsel for the younger boy, Greg Mead, said much of the evidence against the youths was circumstantial and there was no evidence they had possession of, or access to, guns.
He said Facebook conversations between the pair included some discussion about "shooting up a school", talk about suicide and made reference to a "plan", but there was no agreement.
"It's more like two moody teenagers perhaps expressing their dissatisfaction with their lives and with the world," he said in no-case-to-answer submissions.
"It's no more than contemplation, an overly dramatic way of expressing their apparent depressed state of mind."
Those arguments were on Thursday rejected by Ms Sheppard, who remanded both youths in custody for arraignment in the Supreme Court in August.
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