Their bodies were found in a well four days later in their hometown Lakhni in Bhandara district, just 65 kms from Nagpur.
Their grandfather says they were lured away by strangers who promised them food. The girls had lost their father four years ago. Their mother works as a daily wage labourer.
Autopsies on the bodies of three sisters have shown they were raped and murdered. Police have picked up two suspects who knew the girls.
The owner of the farm which has the well had also been questioned, but he does not seem to be involved.
The sisters, students of class V, IV and I respectively, had not returned from school on February 14.
The schools are in Lakhni town, which is just about half a kilometre from the village.
On Sunday, angry local people blocked the highway passing by the village, protesting the failure of the police in nabbing the cuplrits.
Bhandara district is home to the village of Khairlanji, where four members of the Dalit Bhotmange family were tortured and murdered in September 2006, sparking nationwide protests.
