This interaction was captured on May 27 -- just three days before Decker picked up his daughters for a planned visit on May 30. Several days later, on June 2, the three girls -- Paityn Decker, 9; Evelyn Decker, 8; and Olivia Decker, 5 -- were found dead near the Rock Island Campground in Chelan County, Washington, police said.

The video is one of the only clues as to the alleged killer's behavior in the days surrounding his daughters' murders