Leonarde Keeler (October 30, 1903 – September 20, 1949) was the co-inventor of the polygraph. He was named after the polymath Leonardo da Vinci, and preferred to be called Nard. He was a Berkeley high school student and amateur magician. He was captivated by John Augustus Larson's machine, a "cardio-pneumo psychogram", with the goal of detecting deception, and worked on it to produce the modern polygraph.