DENVER (KDVR) — After just one day of witnesses, Devon Erickson’s defense team has rested its case and closing arguments are set to take place on Monday.

Erickson is facing trial, accused of opening fire inside a classroom at STEM School Highlands Ranch and killing classmate Kendrick Castillo and wounding several other people.

A witness for the defense said Friday that Erickson was 50 pounds underweight at the time of the shooting. He was 18 then, standing 5 foot 10 inches tall and weighing 110 pounds.

The defense witness said his condition would cause him to be, among other things, agitated and paranoid.

“You could tell by just looking at him. He was very, very undernourished. Malnourished,” medical consultant Wanda Guidry said.

Guidry spoke extensively about how drugs impact a person’s critical thinking, saying Erickson had a tough time thinking about what he needed or wanted and what was right.

“He had very cloudy thinking,” Guidry said.

Heavy drug use, she said, suppressed his appetite and caused countless sleepless nights.

Prosecutors pointed out that the witness did not examine Erickson or meet him in person and was instead interpreting data.

Prosecutors also pointed out that Erickson had experienced issues long before the shooting, as Erickson reportedly started experiencing depression in the eighth grade.

Erickson is one of two students who were charged in the shooting. Alec McKinney pleaded guilty to his role and testified on the prosecution’s behalf against Erickson earlier this week.

The judge is set to deliver jury instructions at 9:30 a.m. Monday, which will be followed by closing arguments and eventually jury deliberations.