New book traces the killer of Martin Luther King Jr.

Dr. Martin Luther King Jr.
Dr. Martin Luther King Jr. acknowledges the crowd at the Lincoln Memorial for his "I Have a Dream" speech during the March on Washington, D.C. in this file photo of Aug. 28, 1963.
AP Photo/File

Minnesota Public Radio's Stephen Smith interviews best-selling author Hampton Sides about his new book, "Hellhound on His Trail: The Stalking of Martin Luther King, Jr. and the International Hunt for His Assassin."