Friends have reported he was scoping out the Malls. He had been to several with the though of locating the best position to fire from. Apparently he decided on Von Maur in Westroads, because there was a rail where he could stand behind and it was near the elevator. Also, there was a very large open area where there would be plenty of people to shoot at.
In addition Westroads is the largest Mall in Nebraska, and in Omaha there would be a lot of local media and TV stations to cover it. He was looking for attention. This was all premeditated. All planned. It had nothing to do with any previous incident at Westroads. He picked Westroads because it served his purposes.