The preliminary postmortem of the 12-year-old found dead in Baruipur of West Bengal's South 24 Parganas indicates sexual assault, a report said.
The minor girl suffered head injuries and was likely thrown into water alive after being forced inside the sack, the postmortem reportedly indicated.
The girl went missing on Saturday after she left her home in Baruipur to buy a birthday gift for a friend. Her family lodged a missing complaint with the police, and the body was recovered on Sunday from inside a sack in a pond around 25 km from Kolkata.
There were injury marks in the girl's private parts, along with scratch and bite marks across her body, news report PTI quoted the police as saying. The girl's head was either strucjk against a hard surface or struck with a heavy object with the intention of bluedgeoning her to deah, the report added.
Water being found in her lungs and stomach during the examination means she was alive when thrown into the pond. Excessive bleeding from the head injury, along with drowning, are said to have caused her death.
A youth, identified as Indrajit Tanti, 26, suspected of raping and murdering the girl, was intensely thrashed by locals. He was taken to the hospital in a serious condition and was later declared dead.
The main accused in the case, Anand Sardar, was arrested from the Baruipur market area on Monday. Prabhas Mondal and Dibakar Sardar, the other accused, were arrested yesterday. Three others are in detention and are being questioned.