Leonarde Keeler

Leonarde Keeler (1903-1949) was an American inventor and detective, born in North Berkeley, California, who built on the pioneering polygraph work of John Larson to develop and popularize a portable, commercially practical lie detector known as the Keeler Polygraph. On February 2, 1935, he carried out the first documented criminal investigation using his device, in a case involving two assault suspects in Wisconsin, and he went on to head the Scientific Crime Detection Laboratory at Northwestern University before founding the Keeler Institute, the first dedicated polygraph training school. As the first full-time private polygraph consultant, Keeler did more than any other single figure to move the polygraph from an experimental instrument into mainstream use in criminal investigations and, later, employment screening.