Michael Maida, 44, allegedly had inappropriate contact with a student who was under the age of 16, according to a Greenwich police report.
The alleged incident took place in the fall of 2009, according to a release from Convent of the Sacred Heart.
Maida, who has been employed by Sacred Heart for 17 years, denies the allegations, according to the school's release. He has been placed on administrative leave, pending further investigation.
"The safety of our students is our highest priority," Convent of the Sacred Heart director of public relations Kathy Failla said in a statement. "We take all allegations of misconduct seriously and are continually focused on upholding a safe and welcoming environment for our students.
"We have been cooperating fully with the authorities and out of respect for all involved and the important legal process under way, we will not be commenting further."
Convent of the Sacred Heart is an independent, Catholic day school for girls from kindergarten through grade 12 with a coed preschool and prekindergarten, according to its website.
Maida was also an athletic coach at Convent of the Sacred Heart in Greenwich.
Maida has been charged with second-degree sexual assault and risk of injury to a minor, according to police. Both are Class B felonies.
The charge in question applies to sexual intercourse involving a person between the ages of 13 and 15 and someone three years or more older, according to the state penal code.
He was released on $50,000 bond. Maida is due to appear in Stamford Superior Court on March 18.
This article has been updated to differentiate between separate police and school press releases.
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