Writing popular fiction

shoes are freshly polished, but that no one is wearing muddy shoes. Later, it may dawn on the hero that the man with the freshly polished footwear had, just before the interrogation, scrubbed away the traces of mud; his shoeshine could have been to eliminate the evidence. This is, of course, an exaggerated example, but it should give you an idea of how the clue can be presented deceptively, the meaning quietly covered until later.
    A clue may also be introduced with fanfare. A pair of work gloves, covered with garden mud, might be found in the room of the dead man's stepson, for example. This kind of thing is usually used to throw the reader off the track, to get him looking in all the wrong places. Later, it will turn out that the blatantly delivered clue was false; the muddy gloves could have been put there by the killer to throw suspicion on the stepson, or the stepson might have some perfectly legitimate explanation for them.
    Likewise, the very obvious clue can be used to make the reader think: "Well, I'm supposed to suspect the stepson. That much is obvious. Therefore, it couldn't possibly be the stepson." Then, in the end, it is the stepson, after all.
    The idea is to give the reader the pertinent data but to try to fool him into employing it incorrectly. When the real killer's identity is disclosed at the end of the book, the reader should be able to go back, spot check you, and say, "Now, why didn't I see that?"
    9.
Does your narrative tension come from the reader's desire to know
who
more than from his desire to know
how to stop him? It should. The killer's identity, the why of the crime, is more important to the reader than any chase or race against time or anticipation of a violent event. Again, the Nero Wolfe books, or anything by Agatha Christie (especially
The Mystery of the Blue Train, Murder in the Calais Coach
, and
The Murder of Roger Ackroyd)
serves as a fine example of this.
    10.
Does your hero exhaust one avenue of investigation after another until it seems impossible to assign guilt for the crime
? He should reach this point no sooner than halfway through the book. He should seem stumped, or so confused by new developments that the reader almost suspects the killer will get away with his crime.
    11.
Is your police and laboratory procedure genuine
? Does your detective follow established investigatory procedure, as it is known in most public and private police agencies across the country? If you're writing about an autopsy, do you know just how one is done? Do you know what all the police can learn from an autopsy: old injuries, evidence of rape, traces of the killer's skin and hair, a thousand other useless and valuable bits of data? Do you know what surfaces take fingerprints well, what others take them poorly, and which ones don't take them at all? Do you know the different techniques for lifting fingerprints? Do you know how or why a shoe print or tire track can lead the authorities to the villain? All these and hundreds of other things can easily be researched in a university, city, county, or state library. If they do not have any books on criminology, they can borrow them from other libraries for as long as you will need to study them and make notes. One of the best resources on criminology is Jurgen Thorwald's
Crime and Science
, a Harvest Book published by Harcourt Brace Jovanovich in a moderately-priced, over-sized paperback. Thorwald's book is not only a valuable reference work, but an entertaining compilation of famous crimes that were solved through the clever application of forensic science.
    12.
Does your hero's sudden realization of the killer's identity evolve from a juxtaposition of events that he has been playing with, in his mind, all along but which he has been unable to interpret, thus far, because of some preconception or character flaw of his own
? It should. You must never drop the solution into the hero's lap through some twist of fate or stupid mistake made by an otherwise clever villain. His own best efforts should solve the puzzle, his own wit.
    (This is similar to the advice I gave in Section 2 of the preceding chapter, when we were considering the suspense novel. To gain some additional insight on mysteries, you should read Chapter Three as closely as this one.)
    13.
Does the revelation of the villains identity come close to the end of the book
? If it comes in the first third, or in the middle, you are probably writing a suspense novel and not a mystery. Remember,