Det. Dan Nealon speaks at a Toronto news conference on Friday to announce the discovery of a backpack that belonged to Mariam Makhniashvili. (Trevor Dunn/CBC)

The backpack belonging to Mariam Makhniashvili has been found in a parking lot in mid-town Toronto, but there is still no sign of the missing teen.

The black backpack with a green stripe was discovered by "a member of the community," police said Friday, but would give no further details about the person who found the items.

The pack — which was open when police arrived — contained school books and loose-leaf binders belonging to the 17-year-old.

"This is the first tangible item that we've discovered," said Det. Dan Nealon, who is heading the investigation for Toronto police. "And so we're always hopeful that something like this certainly would lead us to the whereabouts of Mariam."

The items were found onThursday in a parking lot behind 120 Eglinton Ave. E. — a building that sits on a busy Toronto street — just a few kilometres away from where the teen was last seen.

Yellow police tape has been strung to block off the parking lot and surrounding area, while police search for any further items that may have spilled from the bag.

Mariam has not been seen since she left her home for Forest Hill Collegiate Institute on the morning of Sept. 14.

She and her younger brother George separated at the back entrance to the school, with Mariam deciding to use the front entrance.

Mariam Makhniashvili and her brother left their native Georgia in June to live with their parents in Toronto. (Toronto Police Service)

Police have been unable to say with any authority what happened to her.

They now hope that video surveillance from nearby buildings in the area near Eglinton Avenue East and Yonge Street might capture an image of the missing teen or whoever put the knapsack in the parking lot.

"We have information [that leads us] to believe that this wasn't the original location where the bag was in the area. And so it could have been moved from in and around one of the condominium areas and placed [in the parking lot]," said Nealon.

Mariam had only been a student at Forest Hill C.I. since the new school year started on Sept. 8.

Her parents said she had not made any friends and that her disappearance is completely out of character for the girl, whom they described as quiet and shy.

Mariam and her brother lived in Tblisi, Georgia, before coming to Toronto in June to reunite with their parents.

The parents, Vakhtang Makhniashvili and Lela Tabidze, arrived in Canada from Los Angeles a few months earlier. The two had lived in the U.S. for five years.

Her father said he remains "hopeful."

"This is, I think … very important, in terms of moving forward in the search. And I was also advised not to make any conclusions, or negative conclusions yet, because it doesn't mean we can make any conclusions about her not being alive," Makhniashvili said.

In September, police released 15 seconds of security camera video of the girl and her brother at Toronto's Union Station on Sunday Sept. 13, the day before she went missing.

Mariam is five feet three inches tall, with light brown, shoulder-length hair and brown eyes. She was last seen wearing black pants, a light blue shirt and a dark blue jean jacket.

Toronto police say they will continue to search and canvas the area for the rest of the day.