Jo Scott-Coe talks about her book, "Unheard Witness," which tells the story of the life and death of Kathy Leissner Whitman, who was the wife of the man who carried out the 1966 mass shooting from the tower at the University of Texas.
For many, the history of mass shootings in the U.S. began with Columbine in 1999. In the quarter century since, there have been hundreds of such shootings, from concerts to