John Larson

John Augustus Larson (1892-1965) was a Canadian-born American police officer and forensic psychiatrist who invented the modern polygraph, becoming the first American police officer with an academic doctorate to employ the device in criminal investigations. After earning a doctorate in physiology from the University of California, Berkeley in 1920, he joined the Berkeley Police Department the same year and developed a comprehensive lie detection instrument by combining an existing blood pressure test with continuous measurements of pulse, respiration and skin conductivity, fully developing the apparatus for forensic use in 1921 and applying it in an actual criminal case for the first time that April. Larson later earned a medical degree and performed psychiatric evaluations within the Illinois correctional system and other mental health institutions across the United States.