Sooo ... turns out I correctly guessed the solution. Though as MbD said in her review, it pretty much turns on one particular item of conjecture presented fairly early on, so I toyed with some more elaborate options for a while because initially I couldn't believe it really should be that easy. -- That said, like MbD I missed a few of the minor clues (and didn't entirely think through, or put a slightly different construction on some of those that I had seen); but ultimately none of that really mattered.
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OK, I've finished it and formed my theory, but since MbD had pity on me last night (her time) and didn't exploit her world clock-generated advantage, I'll put all of my case notes (except for the corresponding headlines) in spoiler tags just to be on the safe side. Though I do have a feeling we're on the same track as far as the solution is concerned. But anyway!
Bolitho Blane and Nicholas Stodart
(show spoiler)
New York (Blane & Stodart's Travel to and Stay There)
(show spoiler)
Crime Scene
(show spoiler)
Time of the Murder
(show spoiler)
Relationship Blane / Hayashi
(show spoiler)
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This particular volume qualifies for square / chapter 4 of the Detection Club bingo, for which I've already read Freeman Wills Crofts's Hog's Back Mystery, but I'm happy to say that I have since found affordable copies of two more books by Dennis Wheatley, as well as Q. Patrick's File on Fenton and Farr online, which I take both from MbD's reviews of Murder Off Miami and File on Fenton and Farr is more intricately plotted, and which will qualify for the "Across the Atlantic" square. Anyway, this was great fun -- and I'm very much looking forward to my next "crime files" adventure!