Mandy and the Intruder

Mandy and her two daughters were murdered in their home. Their mother, doris, was attacked by an intruder who bludgeoned her to death with a four foot pole. The killer then killed the children - emily, 8, and 10-year-old katy. Then he dragged all three bodies of the little girls and their mother on to the upstairs landing. A detective inspector is found at the scene but fails to secure the crime scene. He reports the incident as a fatal house fire, but doesn't inform his superiors that it's also suspected that a family's been murdered,. and that arson has been attempted to cover it up.