COMMERCE CITY, Colo. (CBS4) – At least one mother is upset after a teacher in Adams County was finally charged after being accused of molesting students. She said it could have been prevented if her concerns were heard a decade ago.

“This could’ve been prevented if they would’ve listened to us, if they would’ve helped out,” said one mother of two alleged victims. She didn’t want to be identified.

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Gilbert Joseph Trujillo, 65, is facing 11 counts of sex assault. He was a fourth and fifth grade teacher at Dupont Elementary School in Commerce City but no longer works there.

Gilbert Trujillo (credit Adams County DA)

Gilbert Trujillo (credit Adams County DA)

Authorities said the crimes took place over a six year period starting in 2005 and the victims were 9 and 10-year-olds who attended the school. The allegations include kissing, fondling and inappropriate touching.

“It’s horrible, it’s very horrible because it could’ve been prevented,” said the woman, who told CBS4 that her concerns were not taken seriously.

“A lot of times he had the trailer locked. Once when I went to pick my girls up about 10 minutes before school ended, I pounded and pounded and pounded on the door, but nobody ever answered. A couple minutes later he came to the door and unlocked it. There were four kids in there. I grabbed my two kids and went to the principal. The principal basically told me I was a lunatic.”

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She even tried to confront Trujillo, “I told him I don’t appreciate the door being locked, he said, ‘Oh my pants must have accidentally locked it.'”

Court documents prove the school knew about Trujillo’s alleged inappropriate behavior that included one incident where a student was forced to remove some of her clothes.

In 2008 Trujillo was reprimanded by the Adams Count School District with a list of behavior instructions like “avoid hugging,” no written notes to students and no one-on-one time.

Trujillo resigned in 2011.

“He owes so many kids more than an apology. He took everything from them. Their trust, their livelihood, their independence, their future,” said the mother.

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Trujillo is due in court Thursday for a court hearing. He was being held on a $20,000 bond.