Prosecutors claim Andrew Broadhead, 42, and eight-year-old daughter Kiera were killed after Daniel Jones used petrol to set fire to their home in Wakefield.
It is alleged Jones had broken into a house near to their home on Ash Crescent, Stanley, three days earlier but returned in a bid to destroy possible incriminating footage from a CCTV camera at the property.
Mr Broadhead, his wife Sara, and their two children Kiera, and Mia, 13, had returned from holiday hours before the blaze.
It is alleged that Jones, 29, poured petrol through the front door letterbox and set it alight in the early hours of October 19 last year when the family was asleep.
Jones told the jury that he did not light the fire or carry out a raid on the other house.
Jones , of Spawd Bone Lane, Knottingley, denies two counts of murder, alternative charges of manslaughter and burglary.