New evidence has come to light which suggests that two girls raped and hung in Uttar Pradesh, India, may have been murdered by their family in a so-called honour killing.

The young teenage cousins, members of the Dalit community, were found dead, hanging from a mango tree near their home in Katra Shahadatgani, Budaun on 27 May. Post-mortems found that they had been sexually assaulted, and five men – including two police officers – were subsequently arrested.

The tragic incident has sparked outrage across a country where violence against women is endemic; according to the Asian Centre for Human Rights there are an average of over 4,800 child rape cases in India each year, with victims often being girls from low-castes.

Hundreds protested outside the office of the chief minister of Uttar Pradesh last week, and the UN's resident coordinator for India, Lise Grande, declared that "Violence against women is not a women's issue, it's a human rights issue".

"There should be justice of the families of the two teenage girls and for all the women and girls from lower-caste communities who are targeted and rape in rural India," she added.

Latest reports from police, however, suggest that only one of the girls was raped, and that the double murder may have been conducted by the girls' families, meaning that those arrested for the crime are, in fact, innocent.

Anand Lal Lanerjee, Director General of Police in Uttar Pradesh, told a press conference, "It may be that the crime has another dimension".

According to India Today, Lanerjee suggested that it may have been a case of honour killing, or even triggered by property issues. "Of the two victims, one was the lone child of her parents. Her father is one of three brothers with limited resources and if she was not alive, it could benefit others," Lanerjee said.

"It could be one of the motive. I am not saying that this is the motive," he added.

The Director General also shared that new evidence has been recovered from the site of the attack, and that the current suspects could end up walking free.

A report in the Times of India, however, indicates that the girls' families are "shocked and outraged" by the police's new line of enquiry.

"The police are dancing to the tunes of chief minister Akhilesh Yadav as all the accused are Yadavs. They are out to save those accused in the crime and are twisting the case to save their faces," the father of one of the girls has said.

"We want a CBI inquiry so that the truth comes out."

Reports suggest that the families will now undergo lie-detector tests, and their phone records will be examined.