It is suspected that the victims, Poonam (20) and Swati (12), were strangled to death while they were still asleep in their ground floor residence early in the morning after their parents had left for work, said police.
The incident came to light at around 11 AM.
The prime suspect in the case is a local youth who was allegedly stalking Poonam and had even recently threatened her, police said.
Poonam and Swati lived with their parents Ajit, a security guard, and Rekha, who works at a factory nearby.
At the hospital, doctors found some chits in the inner garments of one of the deceased sisters.
However, the paper is yet to be analysed by the investigating officer, a senior police official said.