A Toronto private school that was warned about the alleged "inappropriate behaviour" of a teacher more than a year before he was charged with sex assaults has asked parents to sign a code of conduct that some say is silencing them, CBC News has learned.

The Waldorf Academy's "Parent/Guardian Code of Conduct," obtained by CBC News, asks signees to "disengage from communication with fellow parents that place blame" and "refrain from 'third party talk', i.e., the passing of information, hearsay and speculation."

"We feel scared to speak," said one parent who asked not to be named. "It's like [the school] is saying, 'be silent and accept whatever we say.'"

The story comes after a CBC Marketplace investigation into the handling of teacher discipline by provinces, which suggested decisions are often kept secret, can take years to resolve and that credentials are rarely revoked.

Several Waldorf parents expressed concern about the code of conduct but did not want to speak about it on the record.

The code of conduct was issued in a March 16 letter to parents obtained by CBC News that came after the teacher was charged earlier this year with sexual assault, sexual interference, sexual exploitation and possessing, making and accessing child pornography.

None of the allegations has been proven in court.

'We were shocked. It's like they were hiding it.' - Waldorf Academy parent

In the letter, the school says the news elicited strong opinions and concerns. 

"While this is understandable, it does not justify some of the behaviours and comments we have seen," the letter said.

The code of conduct is "intended to outline how we will conduct ourselves so that we ensure a positive, safe school climate."

"Conduct deemed inappropriate," the letter reads, "will be dealt with immediately to resolve and repair the situation. If there is no willingness or effort by the parent to work constructively toward a resolution, the School reserves the right to terminate or decline re-enrollment."

The Waldorf Academy did not respond to questions about the code of conduct but issued a statement.

"We have offered counseling to the community, strengthened our protocols and provided additional training to keep our children safe. The safety and well-being of our students has been and always will be paramount at Waldorf Academy," said school facilitator Dean Husseini in the statement on Wednesday.

School received letter about teacher in 2014

The teacher, 41-year-old Ryan McCombe, was charged by Toronto police in January and February for alleged assaults in 2008 and 2012 that occurred outside of the school and involved a 13-year-old girl and then a 16-year-old girl.

But it wasn't the first school administrators had heard of alleged inappropriate behavior involving McCombe.

The school received a letter in September 2014 from an "unregulated psychotherapist" that described an alleged relationship between McCombe and one of the therapist's clients, CBC News has learned.

In a letter to parents, obtained by CBC News, the school says the "anonymous, historical, unsubstantiated claim" gave it "no legal grounds to terminate Mr. McCombe's employment."

The school did not notify police and the teacher continued working at the school up until his arrest in January.

At that point, the school said McCombe was suspended without pay and parents were informed of the letter.

"We were shocked. It's like they were hiding it," a parent, who requested anonymity, told CBC News.

At a January meeting, administrators said the school watched McCombe "like a hawk" after receiving the letter, the parent said.

The parent calls the school's handling of the situation "shameful" and says administrators should have taken the letter directly to Toronto Police.

But a third-party review found the school's conduct after receiving the letter was "reasonable and appropriate in the circumstance."

The confidential review, obtained by CBC News, says the Waldorf Academy notified the Children's Aid Society after receiving the letter, but the CAS did not investigate because the complainant was over the age of 16.

The review says the school questioned McCombe extensively about the alleged behaviour, which he denied, and challenged his responses. The school's lawyer also met with the therapist who wrote the letter and encouraged her to go to police directly.

When asked by CBC News why the police were not notified about the letter in 2014, the school said it was advised by legal counsel at the time that the police would not be able to address the matter.

"Our school has conducted an independent review about whether the steps taken by our school in the handling of this matter, including what our school knew prior to the arrests, were reasonable and appropriate. The investigator concluded that they were, and we shared these findings with our community," Husseini said in the Wednesday statement.