The Silver Dagger Murder Case

Mr. Keen, Tracer of Lost Persons was an American radio drama which aired 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, Dentyne, Aerowax, RCA Victor and Chesterfield cigarettes. It aired on the NBC Blue network until 1947, when it switched to CBS, and was one of the longest-running American shows of the old time radio era.

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“The Silver Dagger Murder Case.” Mr. Keen, Tracer of Lost Persons. Radio broadcast, October 13, 1949.