Parents of students who say they were sexually assaulted by Coquitlam substitute teacher Aleksandr Plehanov are wondering why the school district didn't step in sooner.

One alleged victim's father, who can't be named to protect the identity of his daughter, said the RCMP only found out about the allegations when he called them March 10, six month after another group of parents claim to have complained to the school district.

"I want the district to come clean and let us know what it was that they knew, and when, and change their policy," the father told CTV News.

The Coquitlam School Board refused to discuss the matter at last night's meeting and assured a full room of parents and board meeting attendees that complaints are acted upon appropriately when received.

The district sent CTV News a copy of its five-page document outlining procedures for dealing with unacceptable employee behaviours, which at no point mentions contacting the RCMP.

"I think there's a question here in terms of human resources, in terms of in contract. Suspicion of guilt is one thing, but some sort of evidence is required," B.C.'s director of public school employers Ken Denike said.

But Minister of Families and Children Mary Pollack said teachers and others professionals have a legal obligation to report to police when they have concerns of child abuse.

Parents agree.

"The system failed my child and we're going to everything we can to make sure it won't fail children the next time around," the alleged victim's father said.

With a report from CTV British Columbia's Sarah Galashan