CALGARY -- A man who worked for 36 years with a Calgary young people's performance group has been sentenced to 10 years in prison for sex offences against some of the performers.

Justice Larry Ackerl accepted a joint sentencing recommendation after Philip Heerema, who is 55, and entered guilty pleas mid-trial in January.

Ackerl says Heerema preyed on the young men and his actions were morally despicable and ultimately criminal.

Heerema, who has been free on bail, resigned in 2014 from The Young Canadians School of Performing Arts in Calgary when police began investigating several complaints.

The alleged victims were teen male students who were at the school between 1992 and 2013.

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