A brief history of I LOVE A MYSTERY:

10/2/39 - Moves to evening. 9 storylines aired. 1 episode in circulation.

4/4/40 - Format changes to 30 minutes, once a week, evening. (Still serialized adventures.) On air until 6/27/40, returns 9/30/40. On air until 6/30/41, returns 10/6/41. Gloria Blondell joins cast as Jerry Booker on 3/30/41. Last show with character of Reggie is 2/2/42.

6/29/42 - show leave air. From the 30 minutes period, 9 storylines were aired. 6 episodes in circulation (some are fragmentary)

3/22/43 - Show returns on CBS with Ivory/Oxydol as sponsors. Format returns to 15 minutes, 5 times a week. Jack played by Michael Raffetto (until 5/15/44), Jay Novello (until 8/21/44), then John McIntire. Barton Yarborough plays Doc until 5/15/44, eventually replaced by the character of Michael, played by Forrest Lewis. Gloria Blondell play Jerry until 11/5/43(?), replaced by character of Mary Kay Brown, played by Cathy Lewis.

12/29/44 - Show leaves air. From the second 15 minute period, 24 storylines were aired, 3 episodes are in circulation.

5/21/45 - Audition program taped for 30 minute, complete-in-1 series. Stars Russell Thorson (Jack), Barton Yarborough (Doc). Series not sold. In circulation.

4/25/48 - I LOVE ADVENTURE starts airing. These are weekly complete-in-1 30 minute adventures with Jack and Reggie (later Doc). ABC sustained. Cast is Michael Raffetto (Jack), Tom Collins (Reggie). Reggie is replaced by Doc (played by Barton Yarborough) beginning 6/13/48. Series leave air on 7/18/48 after airing 13 episodes. All are in circulation.

10/3/49 - I LOVE A MYSTERY returns on Mutual. Sustained, 15 minutes 5 times a week. Russell Thorson as Jack until 10/52, then Bob Dryden. Jim Boles as Doc. Tony Randall as Reggie (until 6/12/51). Athena Lord joins cast as Jerry Booker on 2/2/51. Replaced after 4/14/52 by character of Mary Kay Brown, also played by Athena Lord.

12/26/52 - Show leaves air. From the Mutual period, 40 storylines were aired. 38 of these adventures had previously been aired on NBC/CBS runs. In the case where the original airing had been during the 30 minute period of the series, some rewritting was done to refashion the episodes into 15 minute segments. 6 complete or nearly complete storylines are in circulation, in addition another 23 single episodes are available.

5/54 - 3 auditions taped for a return series with Russell Thorson (Jack), Parley Baer (Doc), Ben Wright (Reggie). Series not sold. In circulation.

That's it. Most dates are from Jay Hickerson's ILAM log (highly recommended!)