JB urged me to watch Targets, a movie starring Boris Karloff. It wasn't the usual Karloff fare. Karloff plays an elderly horror-film actor who fears he is obsolete. His story runs parallel to that of a young man who goes on a shooting spree. Both characters feel an urge to completely throw off their former lives. Of course Fate makes these parallel stories meet. (You may think that parallel things should never meet; but Fate can do anything.) As I suspected, the Texas Tower shooting inspired the story.
It was a pretty darn good movie, and it's available to watch instantly from Netflix.