Mr. Keen, Tracer of Lost Persons 1949 The Yellow Talon Murder Case

Mr. Keen, Tracer of Lost Persons was one of radio's longest running shows, airing October 12, 1937, to April 19, 1955, continuing well into the television era.

It was produced by Frank and Anne Hummert, who based it upon Robert W.

Chambers' 1906 novel The Tracer of Lost Persons.

The sponsors included Whitehall Pharmacal (as in Anacin, Kolynos Toothpaste, BiSoDol antacid mints, Hill's cold tablets and Heet liniment), Dentyne, Aerowax, RCA Victor and Chesterfield cigarettes.

It aired on the NBC Blue network until 1947, when it switched to CBS.