Delaine Copenace, 16, was reported missing in Kenora, Ont., on Feb. 28, 2016, and her body was found in a nearby lake almost a month later.
The Ontario coroner determined there was no foul play involved, but a regional coroner later said the investigation was not complete.
Her mother, Anita Ross, says police delayed the search for her daughter and suggested the teen had run away from home.