Toronto police are stepping up their search for missing teen Mariam Makhniashvili with a door-to-door search of her neighbourhood.

Sixty plainclothes detectives will be going door-to-door over the next two to three weeks, seven days a week, 12 hours a day.

Police will be speaking with residents, asking homeowners for access to their residences as they search for clues about the girl who was last seen Sept. 14. Mariam would have turned 18 since she vanished. 

"Expect a knock at your door. Police will keep knocking at your door until they can identify that you are there behind that door," says Det. Sgt. Dan Nealon

Police have also released a new digitally-enhanced photo that reflects what Mariam was wearing the last time she was seen.

Police have searched three parks – Earl Bales, Sunnybrook and Sherwood parks – with a special OPP helicopter on Friday. It was the second time a police chopper was used in what the lead investigator is calling a "very unusual and unique missing person investigation."

The only solid clue so far in the case is Mariam's backpack, which was discovered with some school books in a parking lot on Oct. 8.

On Oct. 27, police seized several computers from two libraries to examine who the girl contacted and what websites she visited.

Mariam's parents have said it's unlikely she ran away since she left home with no money, no passport and no extra clothes.

With files from The Canadian Press