Arthur Conan Doyle used those kinds of clues more than once in his Sherlock Holmes stories. For instance, in The Adventure of the Abbey Grange, Sir Eustace Brackenstall is murdered in what looks like a robbery gone wrong. At first, the notorious Randall gang is suspected of the crime; they’ve been at work in the area lately, and they have a history of break-ins and thefts. But Inspector Stanley Hopkins notices a few odd things about the murder, so he asks Holmes to investigate. Holmes agrees and examines the case. He finds that one clue – a knot – is a clear pointer to the killer, and in the end, he induces the killer to make a confession.
We see another case of clues hiding in plain sight in Agatha Christie’s The Murder of Roger Ackroyd. In that novel, wealthy retired manufacturing tycoon Roger Ackroyd is stabbed on night in his study. His stepson Captain Ralph Paton is suspected of the crime and with good reason. He’s been desperate for money and he had a quarrel with Ackroyd about his finances. What’s worse is that Paton seems to have disappeared. Paton’s fiancée Flora Ackroyd doesn’t believe he’s guilty so she asks Poirot to investigate. When he gets to the Ackroyd residence and begins to look into the matter, he discovers that a piece of furniture in the study has been moved slightly out of place. That fact proves to be very important, but at first, the police don’t pay a lot of attention to it. In the end, that clue gives Poirot a piece of evidence he needs to figure out who the killer is.
In Christie’s Death in the Clouds (AKA Death in the Air), Hercule Poirot is traveling by air from Paris to London. One of his fellow passengers is Madame Giselle, a well-known French moneylender. Towards the end of the trip, Madame Giselle dies of what seems at first like heart failure. And that makes sense, too; there was a wasp flying around the cabin and a puncture wound on her body suggests that she was stung. Soon enough, though, that theory is proved wrong and it’s clear that Madame Giselle was deliberately poisoned. The only suspects are the other passengers who were in the same cabin during the flight, so Poirot and Inspector James “Jimmy” Japp sift through the clues to find out which one of them killed Madame Giselle. There are in this case two blatant clues – right there for the observant reader. Poirot notes one of them right away, but has trouble figuring out why the passenger who has the clue would have a motive for murder. Once Poirot answers that question, he also makes sense of the other obvious clue and finds out who the murderer is.
In Maj Sjöwall and Per Wahlöö’s Roseanna, Stocholm homicide detective Martin Beck and his team are called in when the body of an unidentified young woman is dredged up from Lake Vättern. Eventually, the team discovers that the victim is twenty-seven-year-old Roseanna McGraw, an American tourist who was on a cruise when she died. For months the team works fruitlessly to find out who would have wanted to kill the victim and why. It’s not until Beck figures out that there’s one clue that’s been there the whole time that the police have never really investigated. Once they get to work on that clue, they’re able to narrow down the list of people who could have killed Roseanna McGraw and find the murder.
Henning Mankell’s Faceless Killers also includes a very blatant clue. That’s the story of the brutal murders of Lunnarp farmer Johannes Lövgren and his wife, Maria. Early one morning, Ystad police detective Kurt Wallander and his team are called to the grisly scene of the murder and very soon are given an obvious clue to the killer. The clue, though, is something you could say they don’t want to believe, so although they follow it up, they also look everywhere else they can for the murderer. In fact at one point, the team is so bent on that clue meaning nothing that the detectives focus their efforts on someone else - someone everyone wants to believe is guilty. In the end, though, the most obvious clue turns out to be the one the detectives should have followed in the first place, despite all the pressure to look elsewhere.
Schoolteacher Janek Mitter leaves a very clear clue to his killer’s identity in Håkan Nesser’s Mind’s Eye. Mitter has been convicted of murdering his wife Eva Ringmar, but he can’t remember much at all about the night of the murder. It’s assumed his memory’s been clouded because he was very drunk on the night of the killing but because he doesn’t remember anything, he’s confined to a mental institution instead of a prison. During his stay there, Mitter’s memory slowly begins to return. At one point, he recovers the piece of memory that tells him who his wife’s killer was and leaves a blatant clue to the criminal. But then Mitter himself is brutally murdered. Inspector Van Veeteren and his team, who investigated Eva Ringmar’s death, now have another murder to contend with and even though the murders aren’t identical, the team members are sure that the same person committed both crimes. They begin to look into the lives of both victims and finally, after two months of sifting through clues and tracking down leads, they find the killer. The whole time, they’ve missed a very obvious clue that, had they seen it, would have told them right away who the killer was.
In Elizabeth Spann Craig’s Pretty is as Pretty Dies, retired schoolteacher Myrtle Clover takes it on herself to investigate the murder of real estate developer Parke Stockard. There are plenty of suspects, too, since Stockard was both malicious and greedy. Although Myrtle’s son, police chief Red Clover, doesn’t want his elderly mother to put herself in danger by getting involved in the case, she starts searching for the killer anyway. Without knowing it, the killer gives her a very obvious clue right away. But Myrtle doesn’t notice at the time that she’s been given such a blatant clue, and it’s not until later that she figures out what the clue meant. When she does, it becomes an important piece of evidence.
There are almost always clues to a killer’s identity, and wise sleuths know that sometimes, something that looks like an obvious clue really is a clue. But even the best detectives miss the blatant clues at times. I’ve only had space to mention a few of those obvious clues. Which ones have I missed that you’ve noticed? ;-).