Michael Barta was booked into the Boulder County Jail Tuesday and then released.
The 46-year-old has worked for the Boulder Valley Public School District since 2000 as a counselor at Casey Middle School.
A spokesperson for the Boulder Valley School, Briggs Gamblin, says Barta is on paid administrative leave until the investigation is complete.
"We are very concerned about this, we take it very seriously any time anyone in the position of trust is alleged to have committed a crime such as this," Gamblin said.
The school also sent an e-mail to parents yesterday informing them about the allegations.
According to the arrest report, Boulder Police started their investigation after a phone call on May 14 from a woman who said she was a "professional escort."
She said she had provided services to the person she later found out was Barta. The report says she met him through Craigslist.
The unnamed woman told police, according to the report, she responded to an ad that said:
"I'm a professional male, fit and clean needing stress relief 2-3 times a week. I will be generous in exchange for 5-10 minutes of your time. Drop me a line please."
During the third encounter with Barta, the report indicates he told her about his "deepest and darkest secret," which was to have sex with a 12-year-old girl, according to the police report.
A police officer then answered the ad on Craigslist.
In an e-mail exchange, Barta asked "OK, first of all I need to know if you are over 18. Let me know and I will shoot you my number."
According to the arrest report, the officer answered "Yes, I'm in my 30s."
The two met Tuesday at a Boulder shopping center, where Barta was arrested.
Some students and parents who know Barta came to the school Thursday to show support.
"Everybody loves Barta," said 14-year-old Kim Goldman. "You can just vent to him. He'll joke around and make you feel so much better! He was such a goof ball."
"I don't really care what went on" said Josie Goldman, Kim's mother, "I just know he's the most terrific guy out there. What he does in his private life is his private life."
Barta may be officially charged in August.
He did not return 9NEWS' calls seeking comment.
