Parichay, a student of Class XI, was kidnapped on May 15 when he was on his way to school. Parichay is the son of a landowner, Adarsh Malhotra, based at Kalanaur in Rohtak.
The kidnappers had demanded a ransom of Rs 2 crore from Parichay's father, police said in a release issued here.
Police said they had arrested eight persons in this connection and seized two country-made pistols, two cars, needle and a syringe from their possession.
The kidnappers confessed to the crime and revealed that they had been travelling to different locations with the boy and giving him sedative injections to keep him calm, police said.
The arrested were identified as Rohit, Ajay and Sandeep residents of Gadhipur, Sandeep of Dabauda, Ajay of Bhagibirod, Rajiv of Karnawal, Ajay alias Annu of Bahadurgarh and Sanjeev, a resident of Bihar, police said.