Frustration born of parental negligence since childhood gave way in bed on Sunday night after hours of arguments and requests.

Priyanka realised but too late to wake her sister Alka up from the eternal slumber she had been subjected to.

Interrogation has revealed that killing Alka was not her motive but Priyanka - who wants to be an IPS officer - just could not control her senses as years of importance that her 17-year-old sibling enjoyed at the cost of her negligence was somewhere rooted deep in her mind.

When Alka repeatedly pleaded her Priyanka to accept the marriage proposal by their parents, the 21-year-old girl failed to resist herself.

Priyanka slit Alka's throat and later cut veins in her wrists at their Mohanpur Kachuara home on Sunday night.

'Priyanka, being the only person present in the room where her sister's body lied, was the prime suspect. Initially, she was very aggressive and so was her younger brother Saurabh. Police kept on talking to her and finally the patience paid off with her breaking down, confessing and easing her heart out,' additional superintendent of police (sadar) Ramakant Prasad told The Telegraph.

The police said the family, especially her father Akhilesh Singh, did not give any importance to Priyanka.

'The family had finalised the marriage of Priyanka but she was in no mood to marry. She tried to talk to her family about it but her views were not heard. It was just not about her marriage however. For long, the family had ignored her wishes and aspirations crushing her will all the time. There was a communication gap between her and Akhilesh. The same is the case with Saurabh and Akhilesh. The father only communicated with Alka,' Ramakant said.

'After she confessed to the crime, she said her aspiration was to become an IPS officer. However, her father was in no mood to listen to her or talk to her. Her mother comes from a rural background and she too had very little role to play in the decisions made by Akhilesh,' he added.

With Alka getting all importance always, Priyanka seemed not to like her much. 'All hell broke loose when Alka started advising Priyanka. She was scared mentally and when Alka asked Priyanka that she should listen to their father and get married, Priyanka could not take it any longer. While sleeping, she gagged Alka with her hands and then slit her throat. The injury marks are very deep suggesting that Priyanka took her time as she used the sharp-edged weapon. Then she tried to save herself and slit her wrists too. In fact, she slept in the blood-drenched bed with her sister's body the whole night. It can also be said the family tried to hush up the case,' Ramakant, who was in the interrogating team, said.

Psychologists felt the onus was on the parents.

'One can imagine the mental condition of that girl. With she was not getting any importance, her frustration must have kept on building up and she must have reached a situation when she would mentally explode. The same starts to build up whenever the parents start differentiating between their children which should not happen,' clinical psychologist Binda Singh said.

'All she had in her was anger and she could not control her impulse after both the sisters argued on Sunday night. It is generally seen that parents tend to concentrate more on the younger children while leaving the elder one alone. But in this case, the parents must have crossed the limit. The parents have to think and understand their children,' Binda added.

Another psychiatrist echoed the same: 'Parents should learn how to bring children up,' said the psychiatrist, who did not want to be named.