The trial for a local man accused of molesting eight teenage boys while he was a staffer with The Young Canadians is underway in a Calgary courtroom.

Philip Heerema,55, is facing 20 charges including sexual assault, sexual exploitation and making and possessing child pornography.

He was charged in 2015 after police received a complaint about an inappropriate relationship between a person of authority with the Calgary performance group and a teenager.

Police say the allegations date back to 1992 and eight victims, between the ages of 15 and 18, were identified during the investigation.

Heerema was with The Young Canadians for 36 years and resigned when the allegations were brought forward.

The trial started in a Calgary courtroom on Monday and Heerema's lawyer entered not guilty pleas to all of the charges on behalf of his client.

In her opening remarks, Crown prosecutor, Martha O'Connor, said that the charges in this case are serious.

"The Crown alleges that the accused, Philip Heerema, used his position as the business administrator of The Young Canadians School of Performing Arts, a school operated by the Calgary Stampede Foundation ... to commit sexual offences against the young people who were all at one time students at the performing arts school," she said.

Investigators looked at computers, a cell phone and a camera that were seized from the accused and will testify about what they found.

The victims are also expected to testify during the trial, which is scheduled to last until February 10.

On Monday afternoon, officials with the Calgary Stampede reiterated the organization's commitment to protecting young people.

"The safety and wellbeing of our youth program participants is our number-one priority, and this case is extremely upsetting to us as an organization," said Calgary Stampede spokesperson Kristina Barnes in a statement. "Since first learning of the allegations against the individual, we have fully supported the police investigation."

"Our newly opened performing arts studios include state-of-the-art security features, such as video surveillance, electronically controlled access points, and see-through glass doors on all rooms and offices.  Our programs are built around best-in-class safety practices that we benchmark against peer organizations. Our Life’s Challenges for Youth and Dare to Care programs empower students, equipping them with the tools to speak out against wrongdoing and to report incidents to adults. We also provide students with multiple points of contact, allowing them to reach out to the adult they are most comfortable with to report an incident."