The Case Of The Man Who Invented Death (Aired January 6, 1950) 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. 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. Bennett Kilpack began as Mr. Keen in 1937 with Phil Clarke stepping into the role late in the series. For 18 years the kindly Keen and his faithful assistant, Mike Clancy (Jim Kelly), entertained followers with their intuitive perception that kept listeners coming back for more. With 1690 nationwide broadcasts, Mr. Keen was the most resilient private detective in a namesake role. THIS EPISODE: January 6, 1950. CBS network. "The Case Of The Rushville Murder". Sponsored by: Anacin, Kolynos, Heet, Kriptin, Bisodol, Hills Cold Tabs. A madwoman has escaped from the asylum and committed murder, but what about her sane sister? Frank Hummert, Anne Hummert (originator, producer), Frank Hummert (originator, producer), Bennett Kilpack, Lawrence Klee (writer), Larry Elliott (announcer). 28:47. Episode Notes From The Radio Gold Index.