Uh, I'm back (with something useful to say, but this post starts off a little pendantically, so please bear with me)... Crime fiction finds some of its roots in the tradition of the gothic novel, and the two variously converge and diverge. Poe wrote in a gothic vein and also invented the detective story, more or less. The earliest gothic novels presented mysteries in need of solution -- by rational or supernatural explanation. I'm not sure how this intertwining (or the awareness of it) impacts writers or readers. Some writers today, I think, understand clearly that they are mining overlapping genres; others probably don't think in these terms -- and it doesn't matter. For instance, a serial killer's lair might as well be the dungeon hidden below the castle in a gothic novel. Some gothic novels and crime novels also share similar atmospherics. The grim, foreboding, fated atmosphere of crime novels appropriately labeled "noir" seems a trace of the gothic tradition as well.
And so what? Some readers -- myself included -- enjoy certain gothic effects in their crime fiction. Other readers apparently do not. I recently read Louise Welsh's The Bullet Trick. A while back, I read her debut novel, The Cutting Room. Both books are quite compelling, sordid, and always supported by strong prose. They are crime novels with amateur detectives of sorts (a conjurer in Bullet Trick and an antiques man in Cutting Room), police, and mysteries to be solved. Welsh also mines the gothic tradition -- hidden rooms, props, catacombs of a sort beneath a used bookstore, and so on. Some of the emotional drama too seems gothic, as opposed to the cool understated emotion in some crime fiction. All of these elements work well together in Welsh's hands. I am curious though about Welsh's commercial success, particularly in the U.S. (She is a Scottish writer.) I think I happened on her first book because it won a UK award, but I hadn't heard any word of mouth. It might be that her books are victims to quirks in marketing; sadly, it could be that the dual elements of crime and gothic (in a realistic mode), which give her books their strength and originality (in part), also keep the books from finding some readers. It could be that they are not mysterious enough for some readers, not horrific enough for others, and too seedy for yet others.