I've been visiting independent mystery bookstores to talk about A Perilous Conception. When someone in an audience asked what made me want to write mysteries, all I could do was laugh and say I didn't know.
When I left medical work, I set out to write a mainstream novel whose protagonist was to be Harry Hardwick, a wealthy businessman who lived in New York, and was a fanatical collector of antique music boxes. But as I moved along through Chapter One, someone - I didn't know who - stopped by Harry's house during the night, shot him dead, and stole his most spectacular music box. Over several months, I worked at sneaking Harry past his killer. No luck.
Finally, a writer-friend pointed out to me that I seemed to be trying to write a murder mystery, so why didn't I just let it happen? The result was The Music Box Murders, my first mystery novel. I enjoyed the process, working to create rounded, complex characters with unusual interests who needed to use their specialized skills to work their way through often-ambiguous moral/ethical situations, both to solve a crime and to answer significant questions about themselves and others.
So the decision to write mysteries was not a conscious one, I told my questioner. I just wrote myself into a coroner.