CALGARY -- A former longtime employee of a young people's performance group told police he felt "like a monster" and might have crossed the line with a number of the troupe's members.

Philip Heerema, 55, is on trial facing 20 charges that include child pornography and sexual assault. The alleged encounters are believed to have occurred between 1992 and 2013 with males between 15 and 18 years old.

Calgary police began investigating in January 2014 after they received a complaint from a student and his parents of an inappropriate relationship with a "person of authority" at The Young Canadians School of Performing Arts.

The school works with students between 11 and 18 years old in dance, voice and performance. Training culminates in grandstand shows during the Calgary Stampede every July.

In an interview with police in June 2015, which was played in court Tuesday, Heerema said he considered the students to be friends, but may have gone too far in discussing sexuality with them.

"I feel like a monster. I feel like a horrible human being. These people who I came to know, came to appreciate in my life, came to me and opened up about questions and concerns ... I felt I could open up ... as well and, as you say, I crossed the line," Heerema told Det. Paul Ralstin.

"I never felt like I was trying to manipulate them. I felt I was responding to them and again it was going both ways."

Heerema spent 36 years with The Young Canadians. He started out as a performer and took on a number of jobs that included costuming, props, sets and lighting.

He was business administrator and production services co-ordinator when he resigned after the investigation began in February 2014. He was formally charged 17 months later.

Ralstin sought assurances for the alleged victims in the interview.

"One concern from the guys as well was whether anything got shared with anyone," Ralstin said.

"I swear on my life nothing was ever shared with anyone," Heerema replied. "I hope that if there's anyone else I've had any relationship with they don't consider it assault or abuse. It was never my intent in speaking with them."

One of the alleged victims testified that he got to know Heerema in 1991 and 1992 when Heerema was stage manager. The witness said Heerema and a few other members of the troupe became close friends.

"Phil was a fun guy. It was cool to be friends with Phil. When you're a kid and have a friend that is older it's ... a status symbol that you're friends with one of the teachers," said the man, who is now in his early 40s.

The man said Heerema would take him out to dinner on his birthday and bought him presents, including at Christmas in 1991. Photos of the two men standing in front of a tree were shown in court.

"He bought me cologne and he also bought me several pairs of boxer shorts," the man testified.

He said the two remained close until just before he turned 18 and Heerema took him out to dinner. They went for a walk afterwards.

"We sat down in the grass. He then asked me to lay back. He kind of leaned over," he said. "He put his hand on my lower stomach for a second. He pushed his hand down my pants.

"I jumped. Basically shock happened. I froze for a second and then jumped up. He jumped up. It was pretty awkward. I then asked him to drive me home."

Court heard Heerema spoke to the human resources manager at the Calgary Stampede, which operates the school, when the allegations were first raised.

Susan Garnett said Heerema indicated he was aware of a code of conduct and she questioned him about any relationships he may have had.

"He said, no, he did not have a physical relationship with any of the students," she said.