Five months before the shooting at STEM School Highlands Ranch that killed one student and injured eight others, CBS News learned school Executive Director Penelope Eucker was sent a letter warning about violence and bullying at the school.

The letter was written by a school district official with information from an anonymous parent of a high school senior, who called the district with concerns about the school.

According to the letter, "there is an extremely high drug culture at STEM," and "many students are suicidal and violent." The anonymous parent called it the "the perfect storm" and "expressed concerns about a repeat of Columbine."

The Douglas County School District official said all of the concerns were reported to "the Department of Human Services and to the sheriff's department." STEM school officials disputed the claims and filed a lawsuit in January against the anonymous parent for what they called "defamatory statements."

CBS News could not reach top school officials or the district official who wrote the letter detailing the parent's concerns. However, CBS News confirmed the school district filed a police report based on the concerns and there is an active investigation.

Suspect Devon Erickson, 18, appeared in court Wednesday. The other suspect is listed in court records as 16-year-old Maya McKinney, The Associated Press reported. A public defender said McKinney goes by Alec and uses male pronouns. McKinney is being held on suspicion of murder and attempted murder.