A St. Thomas police officer has pleaded guilty to sexual interference with a minor.

Const. Garry Christiansen, 57, admitted to a having a relationship with a 15-year-old girl.

It began when the teen visited the police station for a background check.

In an agreed statement of facts, court heard that they had a 17-month long, consensual sexual relationship.

He had originally been facing five charges, including assault and sexual assault.

Christiansen resigned from the force on Monday.

He’ll be sentenced in September, when he could get up to 14 years in prison.