Gurugram, June 29 -- The 25-year-old woman whose body was found buried in a pit outside her husband's house in Faridabad was murdered by her in-laws as they suspected she was planning to file for divorce, police said on Saturday, adding that the family feared a legal separation would force them to pay alimony and maintenance, prompting them to conspire and carry out the killing. The woman's 25-year-old sister-in-law has now been arrested for her role in the crime. Her father-in-law and mother-in-law were arrested previously. Her husband is on the run, police said. "After Tannu Rajput was murdered, her sister-in-law Kajal Singh came out of the house at 4am on April 22 to ensure no neighbours were watching. She then signalled her father and brother that the coast was clear, after which they dragged the body out and buried it in a soak-pit," said Mukesh Kumar, deputy commissioner of police (crime), Faridabad. Kajal will be produced in court on Sunday and is likely to be taken into police custody. According to police, the murder was premeditated and orchestrated by the woman's father-in-law, Bhoop Singh, 54, when it became clear that the marriage was collapsing and the woman would likely approach court for divorce. Rajput married Arun Singh, 28, on June 21, 2023, but left for her parental home in Firozabad, Uttar Pradesh, within three months due to domestic disputes and alleged dowry demands. After family intervention, she returned to her in-laws' home in October 2024, but the situation worsened again, said Kumar. "Bhoop wanted to avoid paying alimony, maintenance and wedding expenses up to Rs.20 lakh to the woman's family after divorce and decided to murder her," the DCP said. According to the plan, police said that Bhoop dropped his wife at a relative's house in Uttar Pradesh on April 18. Two days later, he got a soak-pit dug in front of his house under the pretext of installing a sewage connection, exploiting the fact that the neighbourhood was unregularised and such construction could go unnoticed, the DCP said. "On the night of April 21, the family gave Rajput sugarcane juice laced with sleeping pills and after midnight, she was strangled to death in her sleep and the body was buried by Bhoop and Arun after they received the green signal from Kajal," the DCP said. After she fell unconscious, Bhoop Singh allegedly entered her bedroom. According to the DCP, her clothes were dishevelled and he raped her. When he emerged, his son Arun Singh asked if the task was done. Bhoop, panicking, said she was still alive and went back to the room half an hour later, where he strangled her with a scarf. Around 4am, Kajal came out to check for witnesses and gave a signal. Bhoop and Arun then carried the body out and buried it in the soak-pit, covering it with sand, police said. In a further attempt to mislead investigators and delay any suspicion, DCP Kumar said that Bhoop travelled to Rajput's parental home in Shikohabad, Firozabad, on May 26 and dropped a fake letter through their door. The letter claimed to be from Rajput, saying she had eloped with a man who was a computer engineer, and would write again once settled. "He wrote that she had come to the house twice but left without meeting anyone due to shame. But her family didn't believe it-the letter was printed, not handwritten, and bore no signature," Kumar said. Police said Bhoop Singh initially claimed sole responsibility for the murder to shield his family. However, under sustained interrogation, he revealed the roles played by other family members, leading to Kajal's arrest....