I went hunting through Smashwords Read-an-Ebook-Week sale and found a few mysteries on sale whose authors I recognized. This is definitely not an exhaustive list, or even a “recommended” list, since most of these aren’t really my type of thing - just some previously print-published books I found on the way to the sale

. And if any of these duplicate someone else’s posting, I apologize. I didn’t see any of these in this REW thread, anyway.
Lois Greiman has a series with Chrissy McMullen, a psychologist (and former waitress) in Los Angeles. The first several in the series were published by Dell/Random House, but the two on sale at Smashwords seem to be later in the series and seem to be self-published. If I had to guess from the pictures and comments, these seem to be sort of chick-lit mysteries.
Unfortunate seems to be a short story (one reviewer says it isn’t complete), but is free with coupon RE100, and
Uncorked is half off a list price of $7.99 with REW50.
https://www.smashwords.com/books/view/110383
https://www.smashwords.com/books/view/117764
Terry Odell has some books previously published by Five Star, which seem to be romantic suspense. There’s a collection of short stories,
Finding Fire, free with RE100 coupon, and
Finding Sarah is 50% off a list price of $2.99 with code REW50. Also,
When Danger Calls, the first in the “Blackthorne Covert Ops” series (although the author says via SYKM that the order isn’t too important), is not on sale, but is only $0.99.
http://www.smashwords.com/books/view/91298
http://www.smashwords.com/books/view/91297
http://www.smashwords.com/books/view/27275
And William Manchee has a series with Stan Turner, a law student/lawyer (apparently with a brief stint in the Marine Corps too), previously published in paperback by Top Publications (?). I didn't check them all, but the first three in the series,
Undaunted,
Disillusioned, and
Brash Endeavor, at least, are 50% off.
http://www.smashwords.com/books/view/136358
http://www.smashwords.com/books/view/138000
http://www.smashwords.com/books/view/136567
And thanks, ATDrake, for the Nicholson tip – I remember reading one of hers a while back, and will pick up the $0.99 one and the one on sale.