Signature Item Clue
An item belonging to a character is a clue to a character's presence or actions.
In a particular setting something is out of place. A very distinctive something, something that could only have gotten there if someone in particular had been there. For whatever reason, that person came here and did... something. Then, before they left, for some reason, they left the object in question. The types of objects that are left are too many to mention, but they must be distinctive enough to be recognized when they are found. Sometimes they are blatantly obvious, and other times they are the kinds of things that only a Great Detective would notice. Regardless, the implication is that the owner of the object was here, and the object is the proof! Unless it's part of an Orgy of Evidence, planted in a Frame-Up. If it's not a plant, then spotting the item could be followed directly by the owner walking in. It could be a hint that the owner is actually in the room, hiding in the closet. Or the item could be covered with dust, indicating that it has been sitting there for a long time. A variation has the significant item showing up with another person, rather than in a particular place. For example, if you thought Alice and Bob didn't know each other, but then you see Bob carrying Alice's cigarette lighter, you might start to wonder. Although this trope can appear in many contexts, it is a particular staple of detective fiction. This may sometimes bump against Conviction by Counterfactual Clue, if it clinches a case in-story, but the reader is able to figure out other explanations that would establish reasonable doubt. Compare Calling Card, Iconic Item.
- At the end of Miracle on 34th Street, Kris's cane is seen inside the house that Susan insists is her Christmas present, convincing Fred that Kris really is Santa Claus.
- In the movie Life, Eddie Murphy's character sees his father's heirloom pocket watch—the one he lost to the card sharp he was convicted of murdering—in the possession of the deputy who arrested him for the murder, and puts two and two together.
- In Inglourious Basterds, the shoe and autographed napkin left behind by Bridget von Hammersmark when fleeing a bar where several of the Basterds were involved in a fatal shootout with a German officer let Colonel Landa know she was present, when he investigated the scene. The shoe is brought up again later, to von Hammersmark's dismay.
- In Clear and Present Danger Felix Cortez becomes suspicious that the series of attacks on the Medellin Cartel aren't just guerrillas after finding a stray shell casing from one of the US Special Forces' team's M16s at one of the attack sites.
- Blade Runner. Officer Gaff likes to create little figurines and leave them behind. At the end of the movie, Deckard finds a unicorn left by Gaff outside his apartment (in which Rachel was hiding). This showed that Gaff had been there and didn't capture or kill Rachel or notify the other police of her presence the way he should have.
- The Scarlet Pimpernel 1982 had Marguerite, after initially complying with Chauvelin's demands, interfering by warning the Scarlet Pimpernel of danger in the library. Chauvelin discovers this when he finds her earring there.
- Invoked by Abigail in the second National Treasure when she deliberately drops one of her earrings in the Oval Office, then uses that as a distraction for Ben to examine the President's desk, on the grounds that it wouldn't do for an earring belonging to her to be found there.
- In The Searchers, Ethan gives Debbie his medal at the beginning and years later sees it around the neck of the man believed to have kidnaped her. Debbie reappears soon afterward.
- In My Darling Clementine, James Earp shows off a distinctive cross necklace shortly before being murdered; much later, Doc Holliday's girlfriend is seen wearing it, making Wyatt think Holliday was responsible for James's death. (She was actually trysting with one of the real culprits.)
- The Lord of the Rings: Peregrin Took drops his elven brooch while being transported by his orcish captors, in hopes his friends will pick up his trail. The gambit pays off.
- In Beautiful Creatures, Ethan finds Lena's iconic and personalized charm necklace on a beach near the Great Barrier, and know's something must have happened to her and that she passed by that spot.
- In The Convenient Marriage by Georgette Heyer, the heroine is lured under false pretenses into the home of a notorious rake. She manages to escape unscathed, but loses a distinctive piece of jewelry in the process. This is found at the rake's home by one of her enemies, who later produces it as evidence that she must have been there willingly.
- In 1635: The Papal Stakes, the presence of "uptime" casings for shotgun and rifle rounds for use in 20th century gun designs reveals the presence of United States of Europe agents and groups, in investigations by Cardinal Borja's assistant Pedro Dolors into the whereabouts of Pope Urban VII.
- From Rosemary Sutcliff's novel The Eagle of the Ninth: While staying with the people who took the titular eagle from his father's legion, Marcus removes the eagle during the night and hides it under the banks on the edge of a lake, for Esca to return in secret and retrieve days later, after the two of them have been followed and searched. Unfortunately, while doing so, Esca accidentally drops Marcus' distinctive ring-brooch, already "all but torn out" of Marcus' cloak through the roughness of the aforementioned search. When the natives find it days later, they give chase.
- In The Hound of the Baskervilles, the protagonists find the boot used by Stapleton to set the hound onto Henry Baskerville in the Grumpen Mire after he fled, but they didn't find him, and assumed he fell into the mire.
- Older Than Feudalism: In The Bible, Potiphar's wife gets hold of Joseph's cloak as he runs away from her. She later produces the cloak to support her claim that he tried to rape her.
- Subverted in an episode of Due South. There is evidence that a hitman has been watching Fraser's apartment: cigarette butts from his distinctive brand are found near a hallway window in a building opposite where Fraser lives. But the cigarettes aren't stamped out as if the hitman stepped on them, or crushed as if he put them out on the windowsill; they're evenly snuffed, as if the alleged hitman had put them out in an ashtray at an earlier time and then someone else trying to frame the hitman (and Fraser) planted them there - which is exactly what happened.
- In an episode of Babylon 5 Garibaldi goes to find a witness to an attack but someone gets to him first and kills him. Garibaldi is left only with the body, and what appears to be a coat button which is later identified as coming from the coat of a Centauri royal guard.
- In The X-Files, the ash from The Smoking Man's cigarettes have made it clear he's somehow involved a few times (one of the first being when it tipped Mulder off that he'd been in The Mole's car).
- On an episode of Stargate SG-1, SG-1 goes to a planet they've never been to before and find a pack of Russian cigarettes. When they get back they have a little chat with the Russians about what they were doing there and what they found.
- In Othello, the title character is convinced of his wife's infidelity when he discovers that her supposed lover is carrying her distinctive embroidered handkerchief.
- In Shakespeare's Cymbeline Iachimo "proves" that he seduced Posthumus' wife by showing him a bracelet which he claims the wife gave to him; in reality he sneaked into her bedchamber while she was asleep and stole it.
- In Lady Windermere's Fan by Oscar Wilde, Lady Windermere, mistakenly thinking her husband is cheating on her with Mrs Erlynne, goes to her other admirer's dwellings in a moment of weakness. He isn't there, but Mrs Erlynne arrives there and sets her straight. Both women hide when a group of men including Lord Windermere arrive unexpectedly, but Lady Windermere's fan is discovered on the table, recognised by her husband. Fortunately Mrs Erlynne gives herself up, allowing Lady Windermere to escape unseen.
- In An American Tail, Bridget and Tony are looking for Fievel, who got lost during the fire at the pier. Papa Mousekewitz, who had given up his son for dead, refuses to believe that it's the same Fievel Mousekewitz, until he is presented with the hat Papa gave Fievel earlier in the film.
- Tangled: Toward the end, Flynn spots one of Vladimir's ceramic unicorns, letting him know help out of his current situation is at hand. The ruffians from the Snuggly Duckling are nearby, ready to become Big Damn Heroes.
- After Leopold and Loeb disposed of Bobby Franks body, Leopold left his glasses at the scene. These glasses had a unique hinge mechanism that only a few people in Chicago had at the time, leading investigators to him.
Hello, Unknown Troper. You'll need to get known to lend a hand here.