Paul Ovenden, who was the director of strategy at No 10, is understood to have left the role on Monday after a number of instant messages from 2017 became public.
Constance Marten, 38, and her partner Mark Gordon, 51, went on the run with their daughter Victoria to get away from social services after their four other children were taken into care. Victoria's body was later found inside a shopping bag.
The parents of the three girls killed in the stabbing are on Monday giving impact evidence to the public inquiry. Elsie Dot Stancombe's mother Jenni said: "We are one of three families that paid the ultimate price for that day."
The UK said it "unreservedly" condemns the recent incursions into NATO airspace and warned Russia that any further incidents "will again be met with force".
The Victims, Witnesses and Justice Reform (Scotland) Bill faces its final vote at Holyrood, with a lengthy session of more than 160 amendments to be debated ahead of a decision.