Ajmer, May 30 -- A 17-year-old boy was detained, and his 19-year-old sister and mother were arrested on Friday for allegedly killing their father, step-mother, grandmother and cousin, police said on Monday, adding that the accused tried to stage the killings as an accident. Kishangarh Rural deputy superintendent of police Ayush Vashishtha said that the incident occurred on Thursday night. The DSP said that the 17-year-old boy, who is the prime accused in the case, allegedly offered alcohol to his father, which allegedly led to a violent altercation, during which he murdered his father and step-mother, and also killed his grandmother and cousin when they tried to intervene. Investigators say the 17-year-old alleged that years of domestic violence and abuse had driven him to plan the murder. In order to stage the deaths as an accident, he allegedly placed the bodies inside a vehicle and set it ablaze, said the DSP. Investigators said the father of the deceased entered into his second marriage in 2019. He allegedly began to inflict a sustained cycle of abuse on his first wife and children henceforth, said police. The accused reportedly told police that he began plotting his father's murder as a "permanent solution" to the ongoing abuse. The mother and daughter were produced before the court on Friday and remanded to two days of police custody. The minor was detained and presented before the Juvenile Court, which remanded him in custody till before sunset for the investigators to recreate the crime scene and continue the investigation....