Queensland’s more than 600,000 landlords have been warned they could face criminal charges if they ignore tough smoke alarm laws after the owner of the Russell Island home that burnt to the ground killing six people was charged.  Sydney Police allege a man strangled a woman and child to death inside a martial arts studio in North Parramatta before he drove the woman’s white BMW to Baulkham Hills and fatally stabbed her husband on Monday night.  More than a dozen detectives from specialist Melbourne-based units have been assigned to the Samantha Murphy mystery as it emerges as the state’s top priority police inquiry.  Two brothers have saved the lives of a mother and daughter who became distressed while swimming off an Adelaide beach.  See omnystudio.com/listener for privacy information.