Victoria (Tori) Stafford disappeared after she left her school in Woodstock, Ont., on April 8. (Canadian Press)The search for the body of Victoria (Tori) Stafford was in its sixth day Monday as Ontario Provincial Police combed the Guelph Lake Conservation Area in boats and on horses.

The officers, who have been looking for the eight-year-old girl's body after two people from Woodstock, Ont., were arrested and charged last Wednesday, began the search of the conservation area early Monday, the CBC's Stephanie Matteis reported.

"It's slow going," Matteis said. "The Guelph Lake Conservation Area is huge — hundreds of hectares, the size of more than 2,000 soccer fields."

Terri-Lynne McClintic, 18, and Michael Thomas Rafferty, 28, face charges in Stafford's disappearance. (Facebook/Canadian Press)

Police also sifted through rocks on a nearby county road and throughout Wellington County on Monday with the help of Terri-Lynne McClintic, 18, who was charged last week with abduction and being an accessory on allegations she helped her boyfriend Michael Thomas Rafferty, 28, elude authorities.

Rafferty faces charges of first-degree murder and abduction in Stafford's disappearance.

Since the arrests, officers have been searching rural areas north of Guelph with McClintic's help. A court order allowed her to assist investigators in the field but that ended Monday, Matteis said.

Police released pictures Friday of a 2003 blue and black Honda sedan believed to be involved in the abduction. (Oxford Community Police)

On Sunday, police released a photograph of a 2003 Honda four-door car that they say was the vehicle used in Stafford's abduction and murder.

They hope the public in Woodstock, Guelph and surrounding area can help locate the entire back seat of the car, which is missing.

Late Monday, CTV News reported that police were testing for forensic evidence a discarded grey rear car seat that was found in Kitchener, Ont. But authorities haven't confirmed whether the car seat from Kitchener is the one they're looking for.

Stafford disappeared April 8, the day the Grade 3 student was captured on surveillance video leaving her school with a woman who police now allege is McClintic.

McClintic and Rafferty are scheduled to make their next court appearance on May 28.

Anyone with information on the case is asked to call Oxford Community Police at 519-537-2323 or toll free at 1-877-537-6277.