BOULDER COUNTY, Colo. -- Charges have been dropped against a preschool teacher accused of sexually assaulting a young girl.

According to court documents obtained by 7News, Kristen Barnett, 38, passed a lie detector test regarding sexual abuse at the Over the Rainbow preschool in Nederland. The court documents also stated that "an investigation and evaluation by Boulder County Social Services found "insufficient evidence to support by even a preponderance of the evidence a finding that Ms. Barnett was involved in sexual abuse."

Last month, the school was closed because of the sexual assault allegations.

On Monday, The district attorney filed a motion to dismiss the charges.

" ... (T)he People do not believe there is a reasonable probability of proving this case to a jury beyond a reasonable doubt," wrote Boulder County District Attorney Stanley Garnett.

"I am innocent of all allegations of sexual abuse made against me. I am grateful to the Boulder District Attorney and Boulder County Social Services for their thorough investigation of this case and today, justice prevails," Barnett wrote in a statement to 7News. "I am dedicated to early childhood education and I always strived to provide the very best care for the children at Over the Rainbow Preschool. To be falsely accused of a crime against a small child at the school was the most terrible thing anyone can imagine."

Barnett had no prior criminal record when the school was shut down because of the sexual assault charge.

"It was a safety issue for us," Liz McDonough, of the Dept. of Human Services, said on Feb. 2 about closing the school.

An arrest affidavit indicated the sexual assault accuser was a girl and a student, and that the assault occurred at the preschool.

Police began investigating Barnett after the mother of the girl contacted the Sheriff's Office on Dec. 10, and reported her suspicions that a teacher had been inappropriately touching her child during nap time, according to court records.

"The charges against me have caused great harm to my family, my friends and my personal reputation," wrote Barnett.