Four persons have been arrested for the murders believed to have taken place later on Monday night. The sisters' bodies were found the next morning.
The police say the main accused is a boy from another village, who was pursuing the older sister, 17.
The relationship allegedly turned into harassment and stalking after the girl told the boy last year that she was "not interested".
Investigations reveal that the boy, increasingly suspicious that the girl had dumped him for someone else, regularly fought with the girl and also threatened her over the phone.
On Monday night, the boy and three of his friends allegedly got drunk and came to the outskirts of the girl's village. The police say the boys called the older girl to the fields near the village; the girl's family says she went out along with her 13-year-old sister to use the toilet.
The girl's family says the accused had been harassing her for about a year asking her to marry him. They had reportedly gone to the police last year. But it fizzled out after a compromise was worked out between both families by village elders.
The accused reportedly kept trying to intimidate the girl on the phone and in public places.
"We were shocked when a call in the morning informed about their murder. We don't have any enmity with anybody. I don't understand why anybody would kill my daughters," the girls' father had told news agency ANI on Tuesday.
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