Jun 23, 2014 02:48 PM EDT By Russell Westerholm, UniversityHerald Reporter

Aaron Rey Ybarra's attorney is going to enter a plea of not guilty by reason of insanity for her client, who is charged primarily with premeditated first-degree murder.

According to the Associated Press, Ybarra appeared in the King County Superior Court Monday morning for his arraignment. He pled not guilty to charges that carry a maximum sentence of 86 years if convicted on all counts.

King County Prosecutor Dan Satterberg maintains he will seek an extraordinary sentence to put Ybarra, 26, in prison for life.

According to Reuters, authorities said Ybarra shot and killed Paul Lee, a 19-year old student in an academic building on Seattle Pacific University's campus and wounded two more on June 5. As he was reloading, a student security officer subdued Ybarra with pepper spray and tackled the shooter, allowing for other bystanders to help keep him restrained.

Prosecutors have said Ybarra confessed to being the shooter to the police, also telling them he planned to kill as many people as he could before ending his own life.

Satterberg said in a prepared statement he plans to pursue the "rarely used" exceptional sentence "designed for this type of outrageous act of public violence," the Seattle Times reported. Ybarra may be sentenced to life in prison if prosecutors can prove the shooter committed an "offense involved a destructive and foreseeable impact on persons other than the victim."

"The truth is that crime of random and senseless violence took a toll well beyond the student who was killed, those who were injured, and their immediate families," Satterberg said in his statement. "Though it is impossible to measure, I believe that our entire community suffers a profound loss each time there is an incident of mass violence."

According to NBC News, Jon Meis, the 22-year-old engineering student who tackled Ybarra, is being hailed as a hero in the SPU community and beyond. People are even buying him and his fiancé gifts from their registry, after certain users on Reddit found out he was to be married this summer.

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