DOUGLAS COUNTY, Colo. (CBS4)– The defense rested its case in the STEM School shooting suspect Devon Erickson‘s murder trial. He is charged in the May 7, 2019 shooting at the school in Highlands Ranch that left student Kendrick Castillo dead.

Alec McKinney testifies on Wednesday, June 9, 2021. (credit: CBS)

The defense did not dispute that Erickson fired a gun at the school, instead they tried to convince a jury that his judgement was clouded by heavy drug use.

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The defense only called two witnesses to the stand. On Thursday, a psychology professor explained how it is possible that Erickson could have fired the gun involuntarily. On Friday, a toxicology expert testified that Erickson’s thinking was clouded by heavy use of cocaine, THC and perhaps a cough syrup-type drug.

“It is a very potent stimulant much like cocaine. Instead of like a rifle shooting one bullet, it’s like a shotgun effect,” testified Dr. Wanda Guidry.

A day earlier the defense presented its only other witness, a physiologist to say it’s possible Erickson fired involuntarily.

Prior to that the prosecution put on its final witness. Joshua Jones told about the critical moments in room 107. He was one of the three students who tackled Erickson when he pulled out a gun and yelled “don’t anybody f……. move.”

Devon Erickson (credit: CBS)

Jones described when he was shot by Erickson, “We shoved him to the ground I thought that I as falling to the ground.”

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He told the jury how he and Brendon Bialy tried to get the gun away from Erickson.

“How long did you try to peel those fingers off the gun while it’s pointed at your face?” A prosecutor asked. “Oh, like 10, 15 seconds,” Jones replied.

Jones testified co-defendant Alec McKinney then came into the room armed with another gun. Kendrick Castillo, 18, was shot and killed as he went after Erickson.

“I see him kind of rolled over to his side a little bit. I see a teacher, I don’t remember who helping him,” Jones told the courtroom.

STEM School Highlands Ranch Shooting Scene on May 8, 2019

(credit: Michael Ciaglo/Getty Images)

McKinney has already pleaded guilty and testified as a prosecution witness saying he and Erickson planned and carried out the shooting together. The defense has maintained Erickson was under the control of McKinney and threatened him with his life if he didn’t carry out the shooting.

Erickson faces the possibility of life without parole in prison if convicted.

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Closing arguments are scheduled for June 14 before the case will be handed over to the jury.

Rick Sallinger