Kolkata, May 30 -- A 35-year-old civil engineer was arrested for allegedly killing his parents by slitting their throats in West Bengal's East Burdwan district on Wednesday, police officers said on Thursday, adding that the accused had later travelled to North 24 Parganas district where he injured four people by stabbing them. The accused, who studied at Jadavpur University and used to work in Delhi earlier, was caught by the local residents. Police had to rescue him before putting him under arrest, officers said, adding that initial probe revealed that he was mentally unstable. Later, the mob also ransacked the Bongaon police station in North 24 Parganas demanding that the accused be handed over to them, police said. "The accused killed hi...