Constable John Edwards, a team leader with the underwater search unit, told the Toronto Star that sonar was being used to check the bottom of the shallow pond in Woodstock. The pond is just over half a mile from Victoria "Tori" Stafford's school.
The only trace of the missing girl since the end of the school day April 8 is blurry footage captured by a security camera that shows her walking with an unidentified woman. In the video, Tori appears to be accompanying the woman voluntarily.
The provincial police have taken over as the lead agency in the investigation. Local police planned to spend the weekend doing another door-to-door canvass of Woodstock residents because many were away during the Easter weekend.
Tara McDonald, the girl's mother, was to head a march supporting the searchers Saturday afternoon.
Notable deaths of 2014 [PHOTOS]