Dave Moe, a 45-year-old from Denver, was arrested July 24 after federal agents, acting on information gathered online, searched his home, allegedly finding child pornography on a computer and on DVDs and CDs.
Moe has taught at Paddington Station for 18 years. The pricey school, located in the Montclair neighborhood, touts having many teachers trained in the British primary method.
Several parents of current students told 9NEWS they had not been informed of the arrest.
Federal prosecutors, in a written statement issued Thursday, said Moe had been suspected of inappropriate behavior previously.
"Agents and officers learned that there was one allegation of inappropriate contact with a child approximately 10 years ago," the statement read in part. "Nothing was proven."
The 9Wants To Know investigators reached school director Ann Solomon on her cell phone and asked about the prior allegation against Moe.
"I'm in Hawaii. I can't talk," Solomon said, hanging up on the call.
Calls placed to school founder Pippi Hambridge on her work, home and cell phone lines were not immediately returned.
Prosecutors say Moe was teaching "Cultural Rhythms/Enrichments" at Paddington and, since 2005, had served as the school's Director of Enrichments and Before and After School Care programs.
Moe's family said Thursday night that he tells them he is innocent of the charges against him.
The teacher faces charges of possessing and distributing child pornography. He will appear in federal court on Monday.