A 16-year-old accused in a Colorado school shooting pleaded guilty to multiple charges, including murder, on Friday.
Two teenagers, Alec McKinney and Devon Erickson, were arrested after allegedly opening fire at the STEM School Highlands Ranch near Denver on May 7, 2019.
MORE: 16-year-old STEM school shooting suspect to be tried as adult, judge rulesKendrick Castillo, an 18-year-old who tried to confront the shooters, was killed. Multiple students were injured.
McKinney -- who was born biologically female but identifies as male -- pleaded guilty Friday to multiple charges, including first-degree murder, attempted murder and conspiracy to commit first-degree murder after deliberation.
MORE: 20 years after Columbine, what's changed -- and what hasn't -- for school shootings in AmericaThe mandatory minimum sentence is life with the possibility of parole after 40 years minus earned time, prosecutors said.
McKinney's sentencing is set for May 18, prosecutors said.
MORE: 'There's never a safe place': Colorado school training kindergartners to high schoolers to respond to an active shooterErickson, 18, pleaded not guilty. He has a trial scheduled for May, The Denver Post reported.