William Bennett Kilpack (February 6, 1883 – August 17, 1962)

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 (makers of Anacin), Dentyne, Aerowax, RCA Victor and
Chesterfield cigarettes. It aired on the NBC Blue network until 1947, when it
switched to CBS.

Bennett Kilpack (above) began as Mr. Keen in 1937 with Arthur Hughes and
then Phil Clarke stepping into the role later in the series.

Howard Green Duff (November 24, 1913 – July 8, 1990)

The radio series The Adventures of Sam Spade, Detective was 
created by writer Dashiell Hammett for The Maltese Falcon. The
show ran for 13 episodes on ABC in 1946, for 157 episodes on
CBS in 1946-1949, and finally for 51 episodes on NBC in 1949-
1951. The series starred Howard Duff (and later, Steve Dunne)
as Sam Spade and Lurene Tuttle as his secretary Effie, and took
a considerably more tongue-in-cheek approach to the character
than the novel or movie. The announcer was Dick Joy (below).

Dick Joy
(December 28, 1915 – October 31, 1991)