Sibaji Nayak, also a dalit, whose marriage proposal was turned down by the victim's family and against whom a case had been filed earlier for harassing the teenager, was arrested, Dhenkanal Superintendent of Police Mamoranjan Mohanty said.
The body of the teenager of Mathatentulia village was found at a two-room house, 200 metre from her grandparent's home in the village, where she had gone to sleep last night as her parents were away in Cuttack, police sources said.
Her mother Chhani Nayak alleged that her daughter was raped and set ablaze by Sibaji.
The SP said the killer might have set the house on fire with the girl inside to hide the crime.
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He said two more persons would be arrested soon.
The police have registered a case under various sections of CRPC, which includes section 376 (rape) and section 302 (murder).
A case has been registered at the Gandia police station on the basis of the FIR filed by the victim's mother.
The Pipili victim died in July 2012 after remaining in coma since November 2011.