Police said the boy was chopped into pieces with an electric saw.
The parents of Rohan Gucchait, a class VII student at the All Saints High School, Bhiwandi had lodged a complaint with the police on April 17 that Rohan had been kidnapped by some unknown persons.
According to the police, the boy's father Uttambhai Gucchali (39), a jeweller, got a phone call from the kidnappers for a ransom of Rs.50 lakhs.
Later, after learning that the parents had informed police, the kidnappers strangled the boy to death and chopped his body, said the police,
The boy's chopped off legs were found at the Givindwadi flower market. The ossification test revealed that the body parts belonged to a male aged around 12. Later, the boy's father identified the body parts as that of his son, police said.
Today morning, some other body parts of the victim were found in a drain, they said.
The culprits have been identified, police said.