In a rambling, conspiratorial letter addressed to the FBI, alleged assassin Vance Boelter claimed Minnesota Gov. Tim Walz instructed him to kill U.S. Sen. Amy Klobuchar so that Walz could run for the U.S. Senate, according to two people familiar with the contents of the letter. The letter is the clearest evidence yet of Boelter’s mindset after the targeted violence against Minnesota politicians last week. It is incoherent, one and a half pages long, confusing and hard to read, according to two people familiar with the letter’s contents. It includes Boelter alleging he had been trained by the U.S. military...