This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.CASTLE ROCK, Colo. — A teenager charged in the STEM School Highlands Ranch shooting that killed one of his classmates appeared in court Tuesday for a hearing to determine whether prosecutors have enough evidence to go to trial. Devon Erickson, 19, sat next to his lawyers and watched closely as Douglas County Sheriff’s Office Det. Brian Pereira testified at the start of the three-day hearing that revealed some new details surrounding the May 7 shooting. Erickson and 16-year-old Alec McKinney are charged with murder and attempted murder in the shooting that killed 18-year-old Kendrick Castillo and injured eight others. They have not entered pleas to the charges. Authorities say the students entered a classroom through separate doors with guns taken from Erickson’s house and opened fire with at least 29 people inside. A private security guard also injured one of the eight students when he fired at a sheriff’s lieutenant in a hallway during the confusion, authorities said. Castillo was one of the students who rushed Erickson in the classroom, along with Joshua Jones and Brendan Bialy. Castillo’s parents watched the proceedings from the front row of the courtroom packed with members of the school community. Erickson previously said he surrendered his handgun after being tackled by the three students, according to previously released summaries of police interviews with the suspects. However, Pereira testified Tuesday that Bialy told investigators there was a struggle for the gun, and that Erickson had pointed it at their heads. Bialy told investigators that he was able to pry the gun away from Erickson after punching him several times, the detective said. Pereira also said four spent bullet casings were found near Erickson. Erickson previously told police that the impact of three students rushing him caused his gun to fire. Erickson also told investigators that McKinney threatened him and forced him to participate in the shooting by threatening him with a gun and an ax. But investigators did not find evidence corroborating that, according to Pereira. An October hearing has been scheduled for McKinney. Prosecutors charged McKinney as an adult, and his attorneys have said they plan to ask a judge to move the case back to juvenile court.