Those arrested yesterday were identified as Laxmi Narayan Sahu and his parents Rabindra and Laxmi Kumari.
The police seized a kerosene jar and clothes from the house, where Puspanjali was set ablaze.
The victim's father Rajendra Prasad Sahu of Dakhinapur had alleged that his daughter was tortured by her in-laws for dowry, Inspector In-charge of Bada Bazar police station A K Mohanty said.