The Canadian Press

Mariam Makhniashvili, 17, is seen in this image released by the Toronto Police Service.

TORONTO — A provincial police helicopter has finished its search over three Toronto parks today for any sign of missing teenager Mariam Makhniashvili.

The chopper -- equipped with a special high-resolution camera -- spent about an hour in the air over Earl Bales Park, Sunnybrook Park and Sherwood Park just north of the downtown area, as well as a nearby ravine area.

Police are not saying what prompted today's search.

Mariam, whose 18th birthday was last month, was last seen outside Forest Hill Collegiate Institute on Sept. 14.

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.