Const. Garry Christiansen, an officer with the St. Thomas Police Service, has pleaded guilty to one count of sexual interference in connection with his relationship with a then 15-year-old girl.

The 57-year-old appeared at the Elgin County Courthouse on Tuesday. The guilty plea means he gives up his right to a full trial.

Christiansen had originally been charged with five separate counts, including assault and sexual assault.

In an agreed statement of facts, the court heard the then 53-year-old initiated a relationship with a 15-year-old girl who had come in to the police station for a police background check.

After exchanging text messages, they reportedly began a 17-month long consensual sexual relationship that was kept secret.

They would meet at the officer's home, and while the encounters did not initialy involve intercourse, that reportedly changed once the girl turned 16.

The agreed statement of facts also revealed that Christiansen told the victim, "He was afraid of going to jail if she told anyone about their relationship."

Christiansen was arrested in Oct. 2017 after a Crime Stoppers tip the month before prompted St. Thomas police to involve Ontario's Special Investigations Unit.

In a statement, St. Thomas police Chief Chris Herridge said, "This has been a difficult time for the victim, the community and our police service. It is always very disappointing when an officer is charged with a criminal offence, it is disheartening for our members and we understand it is for the community as well."

Christiansen had been with St. Thomas police since 1990, but Herridge added that he resigned on Monday.

He had already been suspended with pay for two years, with the Sunshine List revealing he made $107,000 in 2018 while suspended.

Ontario is the only province that does not allow police chiefs to suspend officers without pay when they face internal discipline or criminal charges.

Christiansen will be sentenced Sept. 18, at which point victim impact statements will also be delivered.

Herridge added, "Every person, regardless of their employment, will be held accountable for their actions...I want to assure the community, especially the victim in this matter, that this is not a reflection of our women and men who work so hard every day to uphold the law and keep our communities safe."