One thing that murderers have in common with the rest of us is that they’re not perfect and they’re not omniscient. They can’t plan for everything That’s how even the best-planned murders are discovered, and even the most careful murderers are caught. Of course, in real life, and in good crime fiction, some murderers are careful and wise enough to avoid getting caught for a while – sometimes even for years. But eventually, murderers often get found out. In police procedurals (Kevin Hughes’ work is an example), the police find the killer through a careful collection and sifting of evidence. But sometimes, the murderer makes mistakes or doesn’t plan well. Those “fatal flaws” in planning can make for an interesting plot point in mystery novels, because they remind the reader that murderers are human, too. That makes the murderer more realistic. It also can be very intellectually satisfying and almost cathartic when the sleuth finds the one mistake that the murderer made, or there’s one complication the murderer hadn’t expected.
Sometimes, the “fatal flaw” in the murderer’s planning comes from a mistake the murderer makes. Modern murderers don’t usually leave fingerprints or make other obvious mistakes. But sometimes, they make the kinds of mistakes in thinking that get the sleuth’s attention. For example, in Tony Hillerman’s Dance Hall of the Dead, Ernesto Cata, a Zuñi teenager, disappears with his friend, Navajo teenager George Bowlegs. When Cata is found dead, George Bowlegs becomes the suspect when he goes into hiding. Lieutenant Joe Leaphorn gets involved in Cata’s murder as he searches for Bowlegs. As he investigates, Leaphorn finds that the Cata and Bowlegs had stumbled onto something far more sinister than just the cultural differences between their Nations. Leaphorn gets an important clue to the murderer’s identity when he finds a set of broken fragments of flint artifacts. His attention’s caught because they’re not broken in the way he would have expected, and that gets him curious. It doesn’t immediately reveal the murderer to him, but it gives him the first clue.
The murderer also makes a mistake in Agatha Christie’s Sad Cypress, only this time, it’s the mistake of saying the wrong thing. In that novel, Elinor Carlisle is accused of poisoning her wealthy Aunt Laura’s protégée, Mary Gerrard. Poirot is called in to investigate by Dr. Peter Lord, Aunt Laura’s doctor, who’s become infatuated with Elinor and wants her to be found innocent. Poirot gets involved in conversations with the witnesses to the murder, and discovers that one of them tells him a small, inconsequential lie. It’s such an unnecessary lie that it draws Poirot’s attention to that witness right away. That mistake doesn’t immediately tell Poirot who the murderer is, but it’s enough to set him on the right path.
We also see a murderer’s lapse of thinking in Ellery Queen’s The Roman Hat Mystery, in which Queen and his father, Inspector Richard Queen, investigate the poisoning death of wealthy attorney and blackmailer Monte Field. The two Queens deduce who the murderer is, but they don’t have any proof – not any proof that will stand up in court. So they trap the murderer into making the mistake of being a creature of habit by getting the killer to try another murder using exactly the same poison and the same method of killing.
In other mysteries, the murderer’s mistake doesn’t come from lapses of thinking, but from events the murderer doesn’t foresee and therefore, hasn’t anticipated. In Agatha Christie’s Hickory Dickory Death (AKA Hickory, Dickory, Dock), for instance, Hercule Poirot is investigating a set of seemingly meaningless thefts at a hostel for students. When one of the residents, Celia Austin, admits that she’s been responsible for most of the thefts, everyone assumes that confession will put an end to the goings-on at the hostel – until Celia Austin is found dead two days later. At first, everyone thinks she’s committed suicide. But Poirot and the police realize she’s been murdered when the manager of the hostel, Mrs. Hubbard, remembers that Celia had filled her pen with green ink the morning before she died. The supposed suicide note was written in blue/black ink. That one unforeseeable event – Celia’s pen running out of ink – gives Poirot an important clue.
In Christie’s Mrs. McGinty’s Dead, Poirot is in the village of Broadhinny, looking for the murderer of a charwoman whom everyone thought was murdered by her lodger. Poirot gets an important clue to the real murderer because of the sloppy habits of the owner of the Guest House where he’s staying. In her haste to find something, she dumps out the contents of a drawer. Poirot, ever a stickler for neatness, puts the drawer’s contents back and slides the drawer in. Then, he goes out. When he returns, his hostess once again upsets the contents of the drawer, looking for something else. When Poirot once again replaces the contents, he finds something there that wasn’t there before, and that gives him an important clue to the murderer. That simple, unexpected event, for which the murderer didn’t plan, is enough to help seal the killer’s fate.
The murderer’s fate is sealed in a different, quite literal way in Robin Cook’s Contagion. In that novel, medical examiners Jack Stapleton and Laurie Montgomery are trying to track down the cause of a series of deaths from nosocomial (hospital-caused) infections. All of the deaths occur at the same hospital, and Jack and Laurie suspect that the deaths are not coincidences. They find that those infections are spread through a deadly influenza virus, and that the virus has been deliberately introduced. As Jack gets closer to finding out who’s behind these deaths, he ends up trapped by the killers. What the killers don’t anticipate, and didn’t plan for, is just how virulent the virus is. In the end, the deadly virus has as much to do with the killers being stopped as Jack does.
The weather can also wreak havoc on the murderer’s plans, as we find in Emma Lathen’s Going for the Gold (my review of that book is here). In that novel, a French ski jumper at the 1980 Winter Olympics at Lake Placid, NY is shot during a jump he’s making. Just after that, John Putnam Thatcher’s informed of a series of counterfeit traveler’s checks that have turned up at the Lake Placid branches of the Sloan Guaranty Bank. Thatcher soon realizes that the two incidences are related and he and police work to find out who the killer is. A sudden blizzard arrives, hampering the killer’s plans to throw suspicion away from Olympic Village, and trapping everyone in Lake Placid long enough for Thatcher and the police to find out who’s committed the murder.
Sometimes, it’s a simple little coincidence that the murderer can’t anticipate that sets the sleuth on the trail. That’s what happens in my book Publish or Perish, which focuses on the murder of a graduate student. Joel Williams, a former police officer-turned-professor, gets interested in the death and works with the Tilton police to solve the killing. One evening, Williams and his are wife are out to dinner when he meets one of the suspects who happens to be at the same restaurant. After dinner, Williams stumbles on an important clue by the pure accident of the suspect’s dead car battery and a jump start that he gives to the suspect.
How do your favorite mystery authors and novels handle that “fatal flaw?” Is that how the killer gets caught? Or do you prefer police procedurals where it’s the evidence that “gets” the killer?