Police are testing a discarded grey rear car seat they found in Kitchener, Ont. for forensic evidence, to see if it is connected to the kidnapping and murder of eight-year-old Victoria Stafford.

Investigators asked the public for help this weekend in locating the rear seat of a 2003 blue Honda Civic -- a vehicle they believe is part of their investigation.

Authorities have yet to confirm the seat they found in Kitchener is the one they have been looking for.

The vehicle, which is blue and partially covered by black spray paint, was spotted in a Guelph, Ont. Home Depot parking lot hours after Victoria went missing from her hometown of Woodstock on April 8.

Police had previously asked the public to come forward if they remembered seeing the vehicle that same day.

Investigators ask that it not be touched, so that it can be preserved in its existing state for use in the investigation.

"It could have some forensic value, there could be some trace evidence on it," Bruce Smollet, a retired staff inspector from the Toronto Sex Crimes Unit, told CTV's Canada AM on Monday.

"If the back seat was taken out prior to Tori being taken it certainly shows some pre-planning."

Lake search

Meanwhile police looking for the missing girl's body have called in a dive team to help search lakes in Guelph and Fergus, Ont.

The OPP Underwater Search and Recovery Unit arrived in Fergus, about an hour-and-a-half northwest of Toronto, early Monday and searched part of the Belwood Lake.

The dive team also went to Guelph Lake for a search.

Three police officers were seen heading out into the murky man-made lake on a small boat with a torpedo-like device called a side-scan sonar.

This device takes an acoustic image of what is underwater and projects it on a computer screen. If police see anything unusual, divers are then instructed to inspect the area.

The search of the lake is not based on any new investigative tips but rather is a sign that investigators are being thorough in their search, a police source told CTV News.

Last week, police charged Michael Thomas C.S. Rafferty, 28, with kidnapping and murder.

Terri-Lynne McClintic, 18, faces charges of kidnapping and being an accessory to murder after the fact.

For the last five days, McClintic has been helping the Ontario Provincial Police find Tori's body in a search radius that covers the span of a 50-minute drive from Guelph, Ont.

The court order allowing McClintic to aid police in the search expired Sunday night.

McClintic's lawyer, Jeanine Roy, said in an email to The Canadian Press that her client is now at the Elgin Middlesex Detention Centre in London, Ont.

Roy said she did not expect McClintic to have any "direct participation in the search."

Rafferty and McClintic are due to appear in court Thursday.

With files from The Canadian Press and a report from CTV Toronto's John Musselman