Patna: A mentally unstable man killed his 35-year-old wife and then died by suicide after locking himself in his room at Madarchak village under Hilsa police station area in Nalanda district on Saturday morning.According to police, Chhathu Ravidas (40) first attacked his wife, Lachhu Devi, with a stone grinder (silwat) following an argument over a domestic dispute, and then pushed her off the roof of their house. Their children, who witnessed the violent altercation between their parents, fled the house and informed neighbours about the incident.Hilsa SDPO, Ranjan Kumar, said, “Upon receiving information about the incident, the local police arrived at the spot. They broke open the room and found Ravidas unconscious. He was rushed to the sub-divisional hospital, where doctors declared him dead.”The SDPO further said that the initial investigation revealed that Ravidas was undergoing treatment for mental illness in a Ranchi hospital about two years ago. At the time of the incident, his parents were in Patna, where his mother was receiving medical treatment. The couple is survived by five children, he said. “While local residents suspect that Ravidas might have consumed poison to kill himself, no evidence of toxic substances was found in the room, nor were there any visible signs such as froth at his mouth. The exact cause of Ravidas’s death will be known after the postmortem. The bodies have been sent to Bihar Sharif Model Hospital for the autopsy. Police have launched a thorough investigation into the case,” the SDPO added.According to police sources, Ravidas was showing signs of mental disturbance for the past few days leading up to the incident.