. >> reporter: ryan young, dayton, ohio. >>> and now steve moore is with us. steve's cnn's law enforcement contributor joining this hour from dallas, texas. steve, good to have you. >> thanks for having me. >> let's focus in on each shooting separately. first, dayton, ohio, the most recent mass shooting. we know that the gunman had a minimal criminal history. that he purchased both weapons legally. was there really anything about his background, steve, that could have tipped off police before any of this happened? >> not that i've seen. of course that's what the investigation's going to produce. when i've worked these shootings in the past, you know nothing about them and it's kind of like writing a biography about them as you go and you find that sometimes, in fact most of the time, signs were missed. >> he killed nine people. including his own sister. injured more than a dozen others, and apparently was wearing a body armor, steve, when police quickly arrived to shoot and kill him. we don't yet know motive, but clearly his aim was to create as much carnage a