(CNN) One of the suspects in the deadly Colorado school shooting is a bully who joked about shootings and threatened other students for years, a former friend said.

Kevin Cole.

Kevin Cole used to go to STEM School Highlands Ranch, where one student was killed and eight others injured Tuesday in a shooting. Two suspects are in custody and will appear in court next week to hear the charges against them.

One of those alleged shooters was Devon Erickson, 18, who was once a friend of Cole's.

"They couldn't believe that he would actually do it, but they weren't entirely surprised that he did," Cole said of the suspect's friends.

Cole told CNN's Scott McLean on Friday that Erickson had a pattern of bullying, violence and jokes about mass shootings.

Read More