One of the Colorado charter school shooting suspects “always joked” about massacring his classmates, a former student says.

Devon Erickson, 18, “would whisper, like get really close and kinda put his arm around you, and whisper in your ear, ‘Don’t come to school tomorrow,'” explained the former student, Kevin Cole, in an interview with “Today.”

“We weren’t surprised who it was because you could kind of see that coming from a mile away, but the fact that he actually did it…,” Cole said. “Because the entire time I was at STEM, he always joked about it.”

Officials at STEM School Highlands Ranch reportedly were warned five months before this week’s deadly attack of a “perfect storm” brewing on campus for “a repeat of Columbine.”

Parents had been complaining about bullying, sexual assault and violence.

“While STEM took the allegations seriously, our investigation revealed no evidence to support any of the allegations raised in the anonymous complaint,” said the school’s executive director, Penelope Eucker, in a statement this week.

Erickson, a senior, allegedly opened fire on his classmates with a pistol — along with another student, Alec McKinney, who is a female but identifies as male — just three days before they were set to graduate. One student, Kendrick Castillo, was killed and eight others wounded.

“Kendrick was definitely one of the people who should’ve survived,” Cole said. “Out of everybody there, he was really the best of us.”

Erickson and McKinney are set to appear in court next week after getting a Friday afternoon hearing pushed back. Their appearance is scheduled for Wednesday.