Tonight, a source tells CNN's John Miller that the alleged UnitedHealthcare CEO shooter made a to-do list for a killing, as well as notes justifying those plans. Law enforcement also said Mangione had a three-page handwritten “claim of responsibility” as police characterized his manifesto. In one notebook passage, Mangione concludes that using a bomb against his intended victim “could kill innocents” but shooting would be more targeted, musing what could be better than “to kill the CEO at his own bean counting conference." Plus, a tip from the public was the key to the apprehension of Luigi Mangione, Randi Kaye takes a look at other high-profile investigations that came to a close with the help of good Samaritans. Learn more about your ad choices. Visit podcastchoices.com/adchoices