Police said on Thursday that a post-mortem investigation had found that the two girls, aged 14 and 15, had been raped and that the cause of death was hanging.
"We have registered a case under various sections, including that of rape, and one of the accused has been taken into custody. There were five people involved, one has been arrested and we are looking for the others," Singh Chouhan, the superintendent of police in the Budaun district of Uttar Pradesh state said.
The two girls, who were cousins, had first gone missing from their home in Katra village on Tuesday evening, when they had gone out into nearby fields as their home has no toilet. They were found hanging in a mango tree by local villagers the next morning.
The girls belonged to the Dalit community, considered the lowest in India's caste system.
The victims' family has accused five men from the village of being behind the killings and police of shielding them from prosecution. The Associated Press reported that the police chief in the village had been suspended.
This is just the latest case to highlight the ongoing problem of sex crimes and against girls and young women in India. According to a report by the Asia Centre for Human Rights released in April of last year, 48,338 cases of child rape were reported in India between 2001 and 2011. Activists say such figures however, are low, due to a culture of tolerance for sexual violence in India, which discourages women from reporting assaults or rape.
A high-profile case in December 2012, in which a 23-year-old woman was fatally gang raped on a New Delhi bus, led to nationwide protests, resulting in the government tightening the country's laws on sexual violence.
pfd/dr (AP, AFP, Reuters)