Delhi: A brother-sister duo were tonight found murdered in their residence in central Delhi, police said. The incident was reported from Ranjit Nagar at around 8.45 PM and the deceased have been identified as Vishal (19), a student, and his sister Shivani (23). The father of the duo found them with head injuries on the first floor of their residence. They were rushed to a nearby hospital where they were declared brought dead. Police have arrested cousin for murdering the duo.