DENVER >> One of two former students accused of a fatal shooting at a suburban Denver school in 2019 was convicted today of over 40 criminal charges, including murder, attempted murder and conspiracy.

The verdict against Devon Erickson came less than 24 hours after lawyers delivered closing arguments in his trial. Prosecutors said Erickson, now 20, was a full partner with Alec McKinney in the shooting that killed one student at STEM School Highlands Ranch in an unincorporated suburban community south of Denver.

The shooting happened in the high school portion of the school in a darkened classroom of seniors watching “The Princess Bride” in the days leading up to graduation. Kendrick Castillo, 18, was killed, and eight others were wounded.

Defense attorneys argued that Erickson, who was 18 at the time, was manipulated and pressured into participating by his younger friend. McKinney testified against Erickson after pleading guilty last year.

Since he was an adult at the time of the shooting, Erickson faces a sentence of life in prison without parole. McKinney, who was 16 at the time, could become eligible for parole after about 20 years in prison under a program for juvenile offenders.

During closing arguments, Erickson’s defense lawyer, David Kaplan, told jurors that the shooting unfolded without a true plan and happened only after Erickson, who was sent to the nurse’s office after he looked sick, got a threatening message from McKinney to help with the attack.

The defense also raised the possibility that Castillo, one of three students hailed as heroes for rushing Erickson after he pulled out a gun, was accidentally shot as he tackled Erickson.

The prosecution disputed the theory, saying an accidental shooting was not likely given the positioning of the two. Two other students struggled to get Erickson to give up his gun after Castillo was shot, prosecutors said.

As the verdict for each count was read, Erickson stood nearly motionless, hands clasped in front of him, staring straight ahead and blinking, as his parents sat in the courtroom. He was wearing a suit and tie and had short, neat brown hair in contrast to the longer, purple hair he had at the time of the shooting.