Mariam Makniashvilli, seen in this Sept. 13 security camera image, was last seen a day later at her north Toronto high school. (Toronto Police Service)

The search for a missing Toronto schoolgirl will resume with added urgency and intensity this week.

Toronto police plan to use an "unprecedented" number of investigators in their hunt for Mariam Makniashvilli.

At a hastily called news conference on Monday, the head of the investigation into the search for the 18-year-old student from Forest Hill Collegiate Institute, Det.-Sgt Dan Nealon, said 60 investigators will go door to door in north Toronto over the next two to three weeks.

Nealon called it "an unprecedented move by the Toronto police command in allowing us to use and have the resources of 60 investigators. What we're going to be doing with the investigators is having an intensive investigative canvas in the area where Mariam lived and where she went to school."

Police have not turned up any firm information about the teen, or information on any suspects, since she disappeared while on her way to school in early September.

An aerial sweep of three Toronto parks on Friday "proved to be negative with respect to finding any evidence in connection to this case," said Nealon.

The only development police have spoken of since Mariam's disappearance was the discovery of her backpack and books in a parking lot near Yonge Street and Eglinton Avenue East about three weeks after she failed to return home from school.

Investigators intend to knock on the doors of about 6,000 residents, said Nealon. They will re-canvass n area between Bathurst Street, Eglinton Avenue, Shalamar Boulevard and Chaplin Crescent.

"We're going to be asking the co-operation of the people who do live there. There will be a large presence of police in your neighbourhood."

The lead investigator said people in the area should "expect a knock at your door ..."

"We're also going to be asking that we be invited inside your home for just a quick peek into areas of your home to ensure that there is no evidence in relation to this case with respect to you — and we can move on, close the door, and go on to the next place," he said.

Mariam, who has turned 18 since she disappeared, was last seen on the morning of Sept. 14 when she headed to school with her brother.

Mariam chose to use a different door to enter the school. She has not been seen since.