Mariam Makniashvilli was last seen on Sept. 14. (Toronto Police Service)

Toronto police are searching a garbage transfer station for clues about the disappearance of Mariam Makniashvilli.

"We have 20 officers at the Ingram transfer station," Det.-Sgt. Dan Nealon told reporters outside 53 Division on Friday afternoon.

Those 20 officers, combined with the 60 investigators sent out earlier this week to canvass door-to-door, represent one of the biggest investigations in Toronto in recent years.

The girl was last seen on Sept. 14 outside Forest Hill Collegiate Institute on Eglinton Avenue West near Bathurst Street. She was 17 years old at the time of her disappearance, but would since have turned 18.

Nealon said the search of the transfer station was prompted by the door-to-door canvass. Police believe that if there is a suspect in the area, evidence may have been thrown into the trash.

"Anyone that's in the area, knowing that police are coming to their door, want to discard any evidence," Nealon said. "This is the reason why we're going to be searching through the garbage."

Police do not have any suspects, Nealon said, but they are hoping to catch a break during the search of the garbage site. "We're looking for any evidence that may be associated to the investigation."

Nealon said this week's decision to send 60 investigators into the area bounded by Bathurst Street, Eglinton Avenue, Shalamar Boulevard and Chaplin Crescent has been met with 100 per cent co-operation from the public. Not one person has refused police entry to their home or property, he said.

The police investigators intend to knock on the doors of about 6,000 residents.

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.

On the morning of Sept. 14, she headed to school with her brother, then chose to use a different door from him to enter the school. She has not been seen since.