There is good reason to question why Mr. Davis was able to show up at the school at all on Friday. In 2015, he cut the throat of an eight-year-old cousin, leading to a first-degree attempted murder charge and conviction on lesser counts. Police say he had been trying to find his cousin, Darelle Yancey, and followed three of the man’s younger siblings asking for him. When they said they didn’t know where Yancey was, he grabbed one of them and cut her across the neck with a knife. He served just three years in prison. Was there any reason to believe someone who would lash out in such inhuman violence against a little girl had been rehabilitated by three years in prison?