The man behind the La Loche shooting was a loner who was often too high on marijuana to work in school, his lawyer argued.

Aaron Fox said those observations came from a statement from a teacher who worked with the shooter and considered him to be depressed.

Fox gave his submissions at a sentencing appeal in Regina on Thursday. The shooter was a few weeks away from his 18th birthday in 2016 when he killed brothers Dayne and Drayden Fontaine in a home in La Loche. He then drove to the school, opened fire and killed teacher Adam Wood and teacher’s aide Marie Janvier. Seven others were injured in the shooting.

Last May, a provincial court handed the then-teenager an adult sentence of life in prison with no chance of parole for 10 years after he pleaded guilty to first-degree murder, second-degree murder and attempted murder.

Fox argues the man should be sentenced as a youth, and that not enough attention was paid to the motive behind the shooting at the original trial.

"I can't imagine something less sophisticated. He basically got in his truck, drove to the school, after he put out a Facebook message saying what he was going to do and what he had already done. There was no effort to disguise, there was no effort to escape, there was no plan to escape," Fox said.

The shooter's journal was depressing and a cry for help, as the shooter described his dislike for school and once wrote a solution for a fellow classmates problems was to form a murder plan.

Tests showed the shooter was operating at a low level of thinking and was using marijuana daily and was self-medicating to deal with his feelings

“The trial judge discounted the fact that he was suffering from depression,” Fox said, adding the shooter had several mental disorders.

The shooter did not progress in school for six years and teachers called him a "mystery box for educators," Fox said.

Fox said a youth sentence would have ensured a treatment plan would have taken place.

The shooter is in maximum security prison in British Columbia, not receiving mental health treatment; a youth sentence would have ensured a treatment plan, Fox said.

Justice Georgina Jackson, Chief Justice Robert Richards and Justice Jerome Tholl are the judges in the appeal.

Chief Justice Robert Richards pointed out that many adults commit crimes at a low maturity level, but Fox responded that his client was a youth and should be treated as such.

Crown prosecutor Bev Klatt argued the use of marijuana was not completely a coping mechanism, as the shooter had said he uses marijuana to calm down.

She argued the judge found the gunman was not bullied and the shooter was adamant he was not bullied.

"This was sophisticated, that everything he did leading up to the murders and what he did on that day were not the actions of someone who was immature or vulnerable or those kinds of things. They were all the actions of somebody who is adapting to a change of circumstances as it was coming, and who had a plan," Klatt said.

While the trial judge acknowledged the shooter's academic challenged and low IQ, a doctor said he didn't stand out for being greatly mentally delayed.

Klatt said the shooter demonstrated a level of maturity and the actions of an adult, and his actions were not impulsive.

The offender cannot be named under the Youth Criminal Justice Act.

The hearing was adjourned early Thursday afternoon. The judges will issue a written decision.

With files from The Canadian Press

CTV Regina's Colton Wiens is at court.