Keeler, Leonard

AMERICAN
POLYGRAPH EXPERT

American scientist Leonard Keeler is widely considered the developer of the polygraph machine. He, along with Berkeley police officer John Larson, was responsible for creating and using the modern version of the polygraph in the 1930s. Although there were minor changes to Keeler's machine since its advent, the basic composition and functions of the machine remained the same until the creation of the computerized polygraph in 1994.

Movement toward the creation of a machine to detect whether a suspect was telling the truth began in earnest around the turn of the twentieth century. In 1885, Cesar Lombroso began measuring the blood pressure of murder suspects. In 1914, two different methods of detecting truth were put into practice—one measured a person's breathing, and one measured the amount of a person's sweat. But it wasn't until the 1930s that work by Keeler and Larson produced what is considered the modern polygraph machine—one that records changes in blood pressure, pulse, respiration, and perspiration as an administrator asks the subject a series of questions. The machine then produces a four-line graph that is analyzed for fluctuations. Keeler, in particular, was responsible for adding a galvanometer to the machine, which measured the skin's electrical resistance. In 1948 Keeler began the first polygraph school, which instructed students on how to conduct and analyze the results of a polygraph test.

As a result of his invention, Keeler began to conduct polygraph tests for law enforcement officials across the country. Keeler used the polygraph on suspect Dr. Frank Sweeney in the Ohio serial murder case known as "The Mad Butcher." In that case he worked closely with well-known detective Eliot Ness. Keeler also tested suspects in the high-profile Colorado murder case of college student Theresa Foster in 1948. Keeler's role in forensic science was even documented in the 1948 film Call Northside 777. The movie is based on the true story of Chicago journalists James McGuire and Jack McPaul, whose series of articles in 1944 and 1945 shed light on the questionable conviction of Joe Majczek for the murder of a police officer in 1932. Keeler, who was involved in the Majczek case, played himself.

see also Film (forensic science in cinema); Polygraph, case histories.