The 15-year-old girl, who was missing for a week, was suspected to have been raped before murder since the body was nude when it was recovered last night, Superintendent of Police Davis Marak said.
Her arms and head were found some distance away and wild animals ate much of her body flesh, he said.
A missing report was filed by her stepfather on September 28, but he was arrested after an FIR was lodged by the girl's mother on October 1, Marak said.
Since his statements were contradictory, his wife lodged an FIR against him, another police offical said.