Two teenage girls were gang-raped then hanged from a tree in a village in the Indian state of Uttar Pradesh.
The incident has caused outrage in the village over police inaction, reports BBC.
One of the victims father claims he was ridiculed by the police when he asked for help in finding his missing daughter, saying that when the policemen found out he was from a lower caste, they refused to look for my girl.
So far three men, including one policeman, have been arrested in connection with the incident.
As the the missing girls, aged 14 and 16 were cousins and from a low caste, the relatives have complained that the police refused to help find them.
The father of one of the girls told the BBC when I went to the police station, the first thing I was asked was my caste. When I told them what my caste was, they started abusing me.
The caste system of Indian has a strong influence in Indian society, violence is often inflicted by the upper castes to instill fear in the lower castes.
Although both the victim and the accused belonged to a caste grouping known as 'Other Backward Classes,' the victims were lower in that hierarchy.
The incident occurred as the victims had apparently gone out to relieve themselves as they had no toilet at home.
Campaigners have highlighted the lack of sanitation in rural areas as being a risk to women's security as well as their health, as they are often attacked when having to go out to go the toilet, particularly at night.
“Two men had been arrested for the rape and murder of the girls,” says police.
Authorities said Aconstable has been detained for conspiring with the suspects and for dereliction of duty.
“They are looking for one more suspect and one constable,” said authorities.
Senior police official Atul Saxena said there would be a thorough investigation into the allegations of caste discrimination by police.
People in Katra Shahadatganj, a town in Badaun district where the incident took place, say caste plays an important role in social affairs in the community.
One resident said if media hadn't come here the police wouldn't have done anything.
A neighbour of one of the victims said the police discriminated against people from the lower castes in the town.
"Even though the police has suspended some constables, the ones who replace them would not be any better," he said.
"The police follows its rule book and considers all criminals equal before the law. There might be one or two cases like this one and we will make sure that the culprit doesn't go scot-free," he said.
Scrutiny of sexual violence in India has grown since the 2012 gang rape and murder of a student on a Delhi bus.
The government tightened laws on sexual violence last year after widespread protests following the attack.
Fast-track courts were brought to the fore to deal with rape and the death penalty was also brought in for the most extreme cases.
Some women's groups argue that the low conviction rate for rape should be challenged with more effective policing rather than stiffer sentences.