Toronto police headed back to a Forest Hill high school Monday to interview students as part of their investigation into the disappearance of local teen Mariam Makhniashvili.

This is the third time investigators have spoken to students at Forest Hill Collegiate. Police have already held two special assemblies at the school asking students to come forward if they have any information.

However, there won't be an assembly on Monday. Instead officers from 53 Division spoke to students individually about the case.

The face-to-face interviews will be quick, said Const. Tony Vella, spokesperson for Toronto police. About 20 officers will take part in the process of interviewing each of 980 students.

Students took home a permission slip to their parents on Friday, principal Peggy Aitchison told reporters. Most parents gave police permission to speak with them in their absence.

It will take police about a week to interview everybody.

"They have a series of questions they are asking the students," Aitchison told reporters outside the school. "I think the idea is to narrow things down to maybe a nucleus of students that may have been in the area where Mariam was the day that she went missing and then maybe have more of an in-depth conversation with those individual students."

Students said they are happy police are taking this step.

"I think this is really good," said one male student. "I know it's pretty late in the case. I'm not sure how many people know Mariam but hopefully they get some information out of it."

Mariam, who was 17 when she disappeared, had only been at the school for four days before she went missing. Most students told police they had never spoken to the girl.

Vella said police are "being thorough" by going back to the place Mariam was last seen.

Latest step

Mariam was last seen Sept. 14 by her brother George. The two walked to their high school from their Bathurst Street and Eglinton Avenue home but when they reached Forest Hill Collegiate, Mariam said she would go to her class through the school's front entrance.

The girl never made it to class and has not been seen since.

"I have to go now. I really don't have time, so sorry," George told CTV Toronto on Monday, before adding that he was okay.

Police say they have no solid leads in the case. Mariam, who moved to Toronto from the Republic of Georgia with her family in June, had not made any friends. Nonetheless her family insists the stable, responsible girl would not have run away.

The only clue so far has been Mariam's schoolbag which was found a few kilometres east of where she was last seen. A passerby found the bag behind a building on Eglinton Avenue just east of Yonge Street.

Last week, police announced they were stepping up their investigation by deploying 60 officers to a door-to-door canvass of the neighbourhood. Officers are asking people to let them briefly into their homes for a quick look. Without such an invitation, they would require a search warrant.

On Friday, police searched the Ingram transfer station for clues. Det. Sgt. Dan Nealon, who is heading the case, told reporters they are searching the garbage site because someone may have thrown out evidence after being spooked by the increased police presence.

Mariam is white, 5'3" with light brown, shoulder-length hair and brown eyes. She was last seen wearing black jeans with front and back pockets and buttons as well as a baby blue, long-sleeved v-neck shirt. She was wearing a waist-length blue jean jacket.

People with information are asked to contact police at 416-808-5300, Crime Stoppers anonymously at 416-222-TIPS (8477), online at www.222tips.com, or text TOR and a message to CRIMES (274637).

With a report from CTV Toronto's John Musselman