The suspect accused of plotting the May 7 fatal shooting at STEM School Highlands Ranch and recruiting a friend to help him carry out the attack has pleaded guilty to numerous felony charges.

Alec McKinney, 16, accepted a plea deal on Feb. 7 and will be sentenced on May 18 for counts including first-degree murder for the death of STEM student Kendrick Castillo, 18.

The plea deal means McKinney will face a minimum sentence of life with the possibility of parole after 40 years and a maximum sentence of life with the possibility of parole after 40 years, plus 409 years in the department of corrections.

McKinney pleaded guilty to first-degree murder, conspiracy to commit first-degree murder after deliberation, six counts of attempted murder after deliberation, attempted murder with extreme indifference, second-degree assault, conspiracy to commit arson, conspiracy to commit burglary, conspiracy to commit criminal mischief, possession of a weapon on school grounds, possession of a handgun by a juvenile and two crime-of-violence sentence enhancers.

Additional charges were dismissed as part of the agreement. McKinney would have faced 43 felony charges if his case had moved to trial.

The teen remained calm throughout his hearing, answering Judge Jeffrey Holmes as he explained McKinney did not have to plead guilty, that he could testify in his own defense at trial and cross-examine witnesses and he was waiving those rights by accepting the deal.

When asked how he would like to plead to the first-degree murder charge for Castillo's death, McKinney looked at the judge and said, “Guilty, your honor.”

The shooting left eight other students injured. Two of the students were injured by a private security guard responding to the incident and are represented in the plea deal by two crime-of-violence sentence enhancers.

John Castillo, father of Kendrick, said the plea deal may have minimized some of the family's pain because they will not have to endure two trials.

“Made life a little bit easier on families,” Castillo said. “So, we can move on to the other perpetrator.”

The family is now mentally preparing to undergo a trial for Devon Erickson, who was 18 at the time of the attack. Erickson is accused of helping McKinney carry out the shooting and pleaded not guilty to 43 felony charges in January.

Eighteenth Judicial District Attorney George Brauchler said the plea deal inched victims closer to receiving justice.

“I'm satisfied with the direction this portion of the case has taken,” Brauchler said.

He noted the sentencing range is wide and discussed a program that could parole McKinney sooner than 40 years.

By state statute, juveniles sentenced to anything can apply for a three-year program in the Department of Corrections that would allow them to be paroled at 20 to 25 years. The program could be available to McKinney even if he receives the maximum sentence, Brauchler said.

McKinney's last appearance was a reverse-transfer hearing spanning roughly one week. Attorneys sought to transfer his case back to juvenile court, which could have changed the type of sentence he received if convicted.

McKinney's mother offered four hours of testimony about his childhood, describing years of abuse. Mothers of students injured in the shooting made tear-stricken statements about the trauma their children had suffered.

Kendrick Castillo's mother, Maria, testified on the final day, telling the judge her life felt over after her son's death. Kendrick was the Castillos' only child.

John Castillo called the reverse-transfer hearing brutal on his family and the other victims.

Douglas County Sheriff Tony Spurlock said the plea deal brought some closure for victims but also brought up painful emotions. Still, he was grateful to hear the suspect admit guilt and take responsibility for the crime, he said.

“We are satisfied. We are fine with this conclusion in this case,” Spurlock said. “This is something that I believe is good for the victims of the crime. It allows one trial.”