The murderers confessed to the killing and surrendered themselves to police along with the murder weapon - a sharp knife.The police moved the bodies to the Jinnah Hospital mortuary and registered an FIR under section 302.Speaking tothe forensic expert at Jinnah Hospital said that there were marks of sharp knife on the necks of the deceased.One of the brothers accused his stepsisters of being involved in prostitution, adding that he and his brother had reservations over their characters.“We have no regrets because we killed them in the name of honour,” the brother said.The other brother said they had previously given warnings to their sisters for their alleged involvement in immoral activities.“We killed our mother because she was supporting them,” he added.SP Saddar Ijaz Shafi Dogar toldthat it seems to be a case of honour killing and that police will carry out investigation covering all aspects.Earlier on November 9, a man had killed his sister and her former husband in Batala Colony area.On October 18, a man axed to death his daughter and injured his wife and brother in People’s Colony after accusing the women of having loose character.