As per the postmortem report, the two sisters were raped before they were hacked to death.
The police has arrested two people in connection with the murders based on the information provided by the deceased women's mother.
Prasanta Mahanta of Naoboisa and Anil Bora of Morigaon district, working with a health NGO are the two people arrested based on the inputs that they visited the house on the night of the murder.
The triple murder surfaced when the bodies of the victims were recovered from their house at Haribordoloni Naoboisa, after the neighbours told the police that the three had not woken up that morning.
The bodies were found without clothes and were reportedly covered with just one blanket.
The women and the baby were alone at the house when they are assaulted as the mother worked in another village while the men of he house work as drivers in Arunachal Pradesh.