jackie dunn: we did. keith morrison: yes and they still wanted to know who owned another car...a red one that was also seen in nikki's driveway the day of the killing. didn't take long to find out. it belonged not to a murderer at all...but a friend. jackie dunn: nikki had missed a hair appointment with this friend, and the friend had come by, knocked on the door and-- not been able to make contact with nikki and left. keith morrison: imagine...had she opened that door. such a grisly scene, so full of rage and passion. so who killed nikki? someone close? then, as they struggled to figure it out, investigators encountered, in their own police files, something rather stunning. craig melvin : coming up: craig melvin : family secrets... there were a few yet to be revealed. yucca harris: it turned into a fight. keith morrison: a physical fight? yucca harris: a physical fight. and she contacted the police. craig melvin : when dateline continues. with dupixent, stay ahead of moderate-to-severe eczema. as you wel