DENVER – Denver school officials refuse to say why they removed a teacher from the classroom with a month left in school.

But an email intercepted by Fox 31 revealed Gilpin Montessori Elementary School teacher Gabrielle Campiformio was on drugs, and three teaching assistants confirmed she repeatedly dozed off in class on her first-, second- and third-grade students.

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Campiformio’s last teaching assistant recorded a video of the teacher struggling to stay awake in early April –  before he quit when school officials refused to take action – and shared the footage with the news site.

“Two students got accustomed to making coffee for her because they were so used to her falling asleep,” the teaching assistant, who requested anonymity, told the news site.

“From seeing her one on one, it’s either drug-related or related to being hung over all the time because it’s just not normal tired to slur your words,” the assistant said.

The teaching assistant told Fox 31 Campiformio would send students for extra recess time when she didn’t want to teach, and many students were suffering academically because of her poor performance.

“After showing the principal the video, she never really addressed the issue with me again,” the man said.

Two other teaching assistants who served in Campiformio’s classroom and quit over her behavior this year confirmed that they also witnessed the teacher’s dazed and confused demeanor, and they also reported it to school officials before tossing in the towel.

“Her voice was slurred, the kids would be like ‘What was that?’ And she would have to repeat again,” Nabil Frano, Campiformio’s assistant from October to February, told the news site. “She couldn’t control her eyes.”

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“It could have absolutely been drug use,” said Campiformio’s first teaching assistant of the year, who also requested anonymity. That assistant said she quit after a month when principal Kimberly Riggins refused to take action, despite the fact that the assistant pointed out Campiformio does not have a license to teach, Fox 31 reports.

“The Colorado Department of Education confirms Campiformio never obtained her teaching license and a spokeswoman said it appeared Denver Public Schools was violating state law by using Campiformio in the classroom,” according to the news site.

Fox 31 went to Campiformio’s home but no one answered. The news site later obtained an email by Riggins to two district administrators sent hours after their visit that said the news site “knew she was on medical leave and was on drugs.”

Fox 31 also uncovered evidence that union officials requested an investigation into Campiformio’s classroom behavior, and that afterwards school officials reported they found no wrongdoing but did not inform the union they suspended the teacher May 2.

Denver Public Schools spokesman Will Jones refused to discuss the teacher’s plight, but said educators in the district cannot be drug tested unless a supervisor suspects use and specifically requests a test.

“A video in itself is not evidence,” Jones told Fox 31. “We have to have someone see it, and they have to see it on the job.”

That someone must be an administrator, not a co-worker, he said.

Jones also alleges the district hires teachers without a Colorado teaching license, but those employees must be working toward a license.

“If we find out that you’re not getting your license,” he said, “that’s when we pull you from the classroom.”

Parents familiar with Campiformio’s problems were irate that principal Riggins received repeated complaints about the teacher but did not remove her until nearly the end of the school year.

“For the principal not to do nothing and know, it makes me mad,” third-grade mother Angel Duran said, adding that she also witnessed the teacher’s disturbing behavior first hand. “Honestly, this year I don’t think my daughter has learned anything. This year I think she’s actually fallen behind.”

DPS officials told Fox 31 they did not renew Campiformio’s teaching contract for the 2016-17 school year.