For example, in Christie’s Mrs. McGinty’s Dead, Superintendent Spence asks Poirot to investigate the murder of a charwoman whom everyone thinks was killed by her lodger James Bentley. Spence doesn’t think Bentley’s guilty, so he enlists Poirot’s help. The first big break in this case is….a bottle of ink. Poirot discovers that Mrs. McGinty bought a bottle of ink two days before she died. That and the discovery of a newspaper clipping put Poirot on the right path. He follows that lead and visits the offices of the newspaper. There, he finds out that Mrs. McGinty had written a letter to the newspaper claiming to have seen a ‘photo just like a ‘photo pictured in a newspaper article she’d read. Eventually, Poirot learns that Mrs. McGinty had discovered something that someone in the village did not want revealed. Once Poirot connects the secret with the right person, he’s able to put the pieces of the crime together.
In The Murder of Roger Ackroyd, Poirot investigates the stabbing death of retired manufacturing tycoon Roger Ackroyd. Several of Ackroyd’s cash-strapped relations and household members are suspects, so it’s not an easy task to find out who the killer is. As if that’s not enough, just about everyone involved in the case is hiding something, so Poirot’s well aware that he can’t depend on what the other characters tell him. As he himself says of such cases,
“Everyone concerned in them has something to hide.”
A small, seemingly insignificant fact starts Poirot on the right path. A piece of furniture in the study has been moved slightly out of place. No-one else sees that as important, but Poirot takes note of it, especially because there seems no logical explanation for that piece of furniture to have been moved. In the end, that small lead turns out to be extremely important in identifying Ackroyd’s killer.
In Maj Sjöwall and Per Wahlöö’s Roseanna, a set of photographs turns out to be the vital clue. In that novel, Stockholm homicide detective Martin Beck and his team are assigned to investigate the murder of Roseanna McGraw, an American visitor who’s been taking a cruise tour of Sweden. When her body is dredged out of Lake Vättern, the field of suspects seems limitless. Even after it’s been established that she was most probably killed by someone on the same cruise ship, this doesn’t do much to solve the case. Any one of over eighty people could have killed the victim, and there’s little to connect any particular person to the crime. Then, in the process of interviewing one of the other passengers, Beck and the team see some souvenir ‘photos that put them, after months of fruitless effort, on the right path. Those ‘photos help to establish the link between killer and victim, and it’s not long before the team focuses in on the right person.
A button turns out to be crucial in linking killer to victims in P.D. James’ A Taste For Death. When Crown Minister Paul Berowne is murdered in a local church, the case is considered quite likely to generate a lot of media attention, since he was a high-profile “celebrity.” So the case is given to Commander Adam Dalgliesh, head of a newly-formed squad specially appointed to handle such cases. Berowne’s body was found with the body of Harry Mack, a tramp who had, it would seem, no connection with Berowne. Dalgliesh and his team members John Massingham and Kate Miskin begin to look in the backgrounds of both men to find out who would have wanted both of them dead. After sifting through the clues and following up on leads, Dalgliesh figures out who the murderer must be. The only trouble is that he has no evidence – none, anyway, that would be admissible in court – to link the culprit to the crimes. Then, by chance, Dalgliesh finds the button that links killer to murders, and is able to catch the criminal.
In Donna Leon’s Through a Glass Darkly, Commissario Guido Brunetti has a similar challenge. He and Ispettore Vianello have been searching for the murderer of Giorgio Tassini, who works nights in a glass-blowing factory. Tassini is convinced that several owners of glass-blowing factories have been illegally disposing of their toxic waste, so when he’s found dead early one morning, there’s more than one suspect. Brunetti and Vianello and their team look into the murder and slowly, Brunetti figures out who killed Tassini and why. But he doesn’t have a lot of proof. And he knows, too, that the murderer is going to be able to explain away the evidence he does have, or gloss it over. This is distressing to Brunetti, because he believes that the murderer is going to get away with a lot. Then one evening, he’s on a boat ride when pilot Paolo Foa happens to mention something about the killer. Brunetti probes with a few questions and it turns out that Foa knows much more than either man guessed about the murderer. In fact, through a friend of his, Foa is able to get a key piece of evidence that connects the killer with the crime. It’s because Brunetti follows up on that slim lead Foa gives him that he’s able to catch the criminal.
And then there’s Adrian Hyland’s Emily Tempest. In Gunshot Road, she’s just begun a new job as an Aboriginal Community police officer. On her first day on the job, Tempest and her team are called to the scene of the murder of prospector Albert Ozolins. Ozolins had had a quarrel with another prospector, John “Wireless” Petherbridge, in a local pub shortly before the murder, and in fact, Wireless is found in a drunken stupor near Ozolins’ body. So at first, it seems obvious that the drunken quarrel went too far and that Wireless is the murderer. But Tempest isn’t so sure that’s true. When her boss, Bruce Cockburn, sends her on what’s supposed to be a routine assignment to get statements from people, Tempest begins to follow small leads that tell her that Ozolins’ death was much more than a drunken brawl gone wrong. Her first lead is a scrap of cloth and other indications that someone was hiding on the hill above Ozolins’ cabin. Then, she notices a strange arrangement of rocks and earth behind the cabin. Everyone else has dismissed it as the work of a slightly crazy man who’d been getting increasingly eccentric. But Tempest thinks it might mean something. Those leads point Tempest towards the beginning of the truth about Ozolins’ death. As it turns out, his death has to do with something much bigger than a quarrel.
In Dorte Hummelshøj Jakobsen’s short story Toffee's Christmas, librarian and vicar’s daughter Rhapsody Gershwin notices that her new neighbour Toffee Brown seems to have left her front door open, and her dog’s running around outside. Rhapsody suspects something’s wrong, so she and her sister go over to see. When they get to Toffee’s house, the women find that she’s been killed. So Rhapsody alerts her fiancé, Constable Archie Primrose. Primrose begins an investigation, but at first, it doesn’t lead very far. The motive doesn’t seem to be robbery, and although there’s a hint that it may be the work of a serial killer, Primrose isn’t sure of that, either. The next day, he asks Rhapsody to take a look at the victim’s books. That gives Archie an important piece of information he needs. Then, while Rhapsody’s there, she sees something else. She tells Archie to follow up on that lead and his willingness to listen to her leads to the killer.
Sleuths don’t always know which leads will take them nowhere and which ones are crucial. So the best sleuths pay attention to every lead they find. Are you good at following up on those important leads, or do you get pulled astray? If you’re a writer, how do you balance being fair to the reader with not giving away the whole story?
*NOTE: The title of this post is a line from Carole King's Where You Lead.