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GPS Evidence

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"I see you found the crumb. I knew you wouldn't notice the enormous flag."
Negaduck, Darkwing Duck, "Just Us Justice Ducks, Part 1"

So your investigation seems to have hit a dead end. Either you have no prints, or you stumbled across a Red Herring, either way the situation seems hopeless...

But wait! The guys at the lab have found the clue you were looking for! Turns out some of the trace in the crime scene is a rare plant that can only be found in a certain part of your town! Or sand that comes from a specific island that one of the suspects has visited recently! Either way, now you're certain where to go. The Lab Rats have stumbled across GPS Evidence.

GPS Evidence is able to pinpoint a certain geographical location with amazing accuracy. It points straight to either the location the heroes are trying to find, or the person they are seeking (if said person was the only person who visited the place that the evidence pinpoints).

While this can border on Deus ex Machina if done badly, the Real Life examples show that there is some Truth in Television to it. Usually goes hand in hand with Sherlock Scan. But compare Sherlock Can Read if what you actually found was a piece of text labeling the thing's location.


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    Anime & Manga 
  • Used a couple of times in JoJo's Bizarre Adventure: Stardust Crusaders. First, the actual adventure is kicked off when Star Platinum spots an insect native to Egypt in Joseph's psychic photo of Dio. Once in the country, the group acquires a photo of Dio's mansion and asks around to find its location, attracting the attention of one of Dio's henchmen who later admits to their destination being in lower Cairo.
    • In the manga, the photo is also given to a (professional) beggar who does manage to find the mansion on his own. He's picked off by another of Dio's subordinates before the information can be relayed.

    Comic Books 
  • Done too often to list by Batman. Gotham City must have some truly bizarre geology given the number of soil types unique to one area of the city.
  • Spoofed in Superman & Batman: Generations in the chapter depicting the eponymous heroes' first meeting in 1929. Superboy uses his microscopic vision to analyze a crate for clues while Robin (Bruce Wayne) says that they can track the sender using Superboy's findings. At this point, Lois Lane names the crate's exact point of origin... by reading it off the shipping label.
  • Star Wars: Darth Vader: Vader arranges for funds confiscated by the Empire to be "lost" in transit so he can use them to fund his own agenda. Not only does General Tagge realize the money was stolen and order Vader himself to find the one responsible, but Vader's new adjutant, Inspector Thanoth, deduces Vader was on a nearby moon at the time of the theft. How? The slight ionization of surface dust on his armor.

    Fan Works 
  • Triptych Continuum: In Glimmer, one of the oddities about Lynchpin's corpse is a specific kind of rash caused by exposure to the oils of the flamethorn tree, which only grows wild in a few countries in Menajeria's southern hemisphere.

    Films — Animation 
  • Downplayed in Cars 2 where a special piece of evidence clues Mater into the identity of the Big Bad. After the Lemons bolt a bomb into his air filter to try and kill McQueen, he gets a "Eureka!" Moment after Guido fails to remove the bomb since they used an old brand of bolts which have an unconventional size that don't match many common tools, Mater realises that these were the same brand of bolts used by the Lemons' leader which combined with his oil-leaking incident in Japan, leads him to correctly deduce it's Sir Miles Axelrod after he threatens to blow both of them up unless he disarms the bomb.
  • In The Great Mouse Detective, a Mouse World version of Sherlock Holmes, the combination of three substances on a piece of paper are used to pinpoint a villain's hangout, the only bar (brandy) located where the sewer (coal dust) meets the river front (salt water). It could of course have been dropped by a coal deliveryman who'd treated himself to a Quick Nip and bought a bag of chips on his way home from work, but hey.
  • In Disney's Mulan, Shan-Yu's falcon brings him a doll from a village to which they are en route. The doll has evidence on it — pine tar, a white horse hair, and sulphur from cannons — that tells him the location of the village and that the Imperial Army are there.

    Films — Live-Action 
  • In Ace Ventura: When Nature Calls, Ace gets shot by multiple darts and suspects the darts are being shot by the Wachootoo tribe. After the scene with the tribe, he gets shot again and finds out the Wachootoo dart didn't match the original darts. Ace discovers the original dart was carved from a "red, fungus-bearing acala" which is grown only in one area in the jungle where the bat-nappers are hiding.
  • In Austin Powers: The Spy Who Shagged Me, Austin finds the location of Dr. Evil's lair due to a specific plant found in Fat Bastard's stool sample.
  • In Charlie's Angels (2000), one of the Angels hears a bird call on a tape sent by the bad guys, and recognizes it as a species that only lives on one very small island. Except she identifies it as a pygmy nuthatch, which isn't even close to rare, and lives pretty much everywhere in California.
  • In Fast & Furious, Dom looks at the crash scene where Letty (allegedly) died, and finds ash of a peculiar color which he recognizes as coming from a meth-nitro afterburner system. That part is fairly plausible since as a former champion street racer, he would know a lot about exotic car modifications. But from that clue, he then immediately figures out exactly what garage the person responsible for the crash went to. This despite the fact that 1: The idea that there is literally only one mechanic willing to do a particular car mod in a region as heavily populated as the LA Metro area is ridiculous, and 2: Since Dom hadn't been to LA in five years, even if it had been true when he last lived there, there was a good chance it wasn't true now. It still works.
  • In The Fugitive, Gerard and his men get a wiretap recording of Kimble calling his lawyer. As they listen, Henry and another marshal hear the sounds of an elevated train in the background. This helps them narrow down his location to cities with such trains. Enhancing the tape provides them with a specific city when they discover a PA system in the background announcing "Next stop: Merchandise Mart," telling Gerard and his men that Kimble is back in Chicago.
  • In Jack the Ripper (1976), the pine needle found clutched in the dead woman's hand comes from an Indian species; the only examples of which in London are in Kensington Gardens. This tallies with the scent the blind man Mr. Bridger had smelled on Jack.
  • James Bond knows to search the Amazon jungle for Drax's secret base in Moonraker — it's where the specific orchid used in Drax's neurotoxin came from.
  • The Naked Gun:
    • Parodied in the series when the scientist involved outlines his plan to do an exhaustive study and analysis of the city's soil sample from a footprint found at the crime scene. When the police tell him that they don't have time for him to run his tests, the scientist helpfully suggests getting the criminal's address from the driver's license in his wallet, also found at the crime scene.
    • And again when Ted the lab guy tries to analyze the wood fiber in a message from their suspect and determines that it came from a specific tree found only in one region and used as raw material in only one paper mill. The trail unfortunately went cold from there, so it's a good thing the message had their suspect's address on the letterhead, eh?
  • Guy Ritchie's Sherlock Holmes films have variants of this trope.:
    • In the first film, members of the Temple of the Four Orders bail Holmes out of jail. As soon as Holmes gets in, a man apologetically puts a bag over his head. When it's removed, Holmes is sitting in front of Sir Thomas in the Temple's headquarters.
      Sir Thomas: Mr. Holmes, apologies for summoning you like this. I'm sure it's quite a mystery as to where you are, and who I am...
      Sherlock Holmes: As to where I am? I was, admittedly, lost for a moment, between Charing Cross and Holborn, but I was saved by the bread shop on Saffron Hill. The only baker to use a certain French glaze on their loaves — a Brittany sage. After that, the carriage forked left, then right, and then the tell-tale bump at the Fleet Conduit. And as to who you are, that took every ounce of my not-inconsiderable experience. The letters on your desk were addressed to a Sir Thomas Rotherham. Lord Chief Justice, that would be the official title. Who you really are is, of course, another matter entirely. Judging by the sacred ox on your ring, you're the secret head of the Temple of the Four Orders in whose headquarters we now sit, located on the northwest corner of St. James Square, I think. As to the mystery, the only mystery is why you bothered to blindfold me at all.
    • Holmes determines from trace clues on Lord Coward's clothing what he's done and the fact that he's been helping Blackwood set up a machine in the sewers to assassinate Parliament.
    • In the second film, when looking at some letters that Simza's brother Rene has sent her, Holmes and Watson notice that they are of the stock used by a printing press, and are musty, as if stored in a damp place. A wine stain on one of the sheets allows Holmes to conclude that they were from a wine cellar near a printing press, which is how they locate the anarchist leader Claude Ravache.
  • Star Wars Episode II: Attack of the Clones has a perfectly sensible example, as pinpointing which planet a rare weapon came from is quite a lot easier than most of the examples here.
  • Referenced in the film of V for Vendetta. V says he can't let Evey leave because though she was unconscious when he brought her to his home, she's seen the color of the stone in the underground lair, and the government would be able to find him with that information.
  • In Pineapple Express, Dale sees drug lord Ted kill a man and go on the run, leaving behind a roach of marijuana at the scene. This roach is full of a very rare kind of marijuana named "Pineapple Express", only sold by Ted, and who sold it to only one dealer in the entire valley — Saul, Dale's friend. Half an hour later, Dale and Saul barely escape with their lives when Ted's goons come kicking down the door.
  • In Room, a cop is dealing with Jack, a traumatized boy who has just escaped his kidnapper and now has lost his way in a totally alien environment. While Jack is completely disoriented and convinced he has lost his one chance to help his mother, the cop is able to get from him a handful of vital clues: the trip he had in the kidnapper's truck made three stops, and he and his mother were held in a shack with a skylight. The cop concludes that Jack's mother must likely be in a three-block vicinity in a small building with a distinctive and easy-to-spot roof feature. With that information, the police are able to rescue Ma that night.
  • Sir Arthur Conan Doyle's Sherlock Holmes: After the mechanical dinosaurs blow up the rubber factory, Holmes finds a pebble clinging to the owner's body which, because of its lack of singeing, had to have become attached to his clothes immediately before he was flung through the window. It is a type of rock found in only one place in Britain, which happens to be near Holmes' boyhood home. Given we later learn that the Big Bad is Sherlock's brother, it is entirely possible it was placed there deliberately for Sherlock to find.
  • In White Sands, a bit of carpet fuzz on a body found in the desert is traced to the motel where he was staying.

  • Not uncommon in Ellis Peters' Brother Cadfael novels. In The Leper of St. Giles, Cadfael discovers traces of three different varieties of plants on a corpse and surmises that the body was murdered in an area where all three plants grow closely together.
  • Quadriplegic Forensic Expert Lincoln Rhyme, from the Jeffrey Deaver novels, seemingly has samples of everything in the city. Most notable in The Bone Collector, where he can narrow dirt samples down to a particular building.
  • Frequently subverted in the Discworld books featuring the Night Watch:
    • In Thud!, Angua smells clay from Quarry Lane, the home of a large part of the Ankh-Morpork troll community down in the dwarf mine. She however remembers Vimes philosophy on clues: "Don't trust them, you could walk around with pockets full of them." It is a really important clue for that reason, because it tells them a dwarf is trying to frame the trolls.
    • In The Fifth Elephant, Reg Shoe remembers Vimes' advice as well when investigating the murder of rubber goods manufacturer Sonky. One must beware of trusting clues too much, otherwise one might find a wooden leg, a pink slipper, and a feather and "hatch up a theory involving a one-legged ballet dancer and a production of Chicken Lake".
    • Jingo:
      • Klatchian coins and sand in the room of the man suspected for the assassination attempt of the ambassador is supposed to be seen as proof that "Someone in Ankh-Morpork did a bad job trying to frame the Klatchians". It turns out to be "Klatchians are smarter than Morporkians give them credit for."
      • Played straight: Angua can smell a particular dye on the coat belonging to an assassin (not to be confused with an Assassin) which she knows comes from a specific city and is important in discovering said assassin's identity.
    • In Feet of Clay: Angua and Cheery bring some clay from a crime scene to a pottery hoping that there's lots of different kinds or something, but are disappointed to be told that "It's just clay." However, double-subverted in that they also learn where it's from in the process, and this turns out to be an important clue.
    • Played With in Night Watch, where Vimes is shown to be able to tell where in the city he is by feeling the brickwork on the road through thin-soled boots since he spent decades patrolling the city while wearing cardboard-soled boots.
  • A staple of the methods used by Sherlock Holmes. Among them, he's done studies on soil composition on a large radius from London and he can notice and identify tattoo styles from around the world and can pinpoint a perpetrator's whereabouts down to a pretty good range. Given that modern forensics owes something to Holmes (Doyle wrote about fingerprint and blood analysis years before anyone used it for real) it may be a Trope Maker.
  • Heralds of Valdemar: An artist-slash-assassin in Storm Warning gives himself away when he mentions the use of a certain pigment in his work — which comes from a mineral found only in the Eastern Empire for which he is The Mole.
  • K is for Killing by Daniel Easterman. A spy is forced to kill an American police officer after landing by submarine in the United States. He throws up afterwards, and an analysis of the stomach contents shows that he was drinking ersatz coffee shortly beforehand, then only used in Europe.
  • Deliberately done by the Eco-Killer in The Killing Hour - he kidnaps two women, one he murders and dumps in an easy-to-find spot and the other he abandons alive in a deadly, remote place. He leaves clues to the living woman's location on the body of the dead woman, as a challenge to see if the detectives can track her down before she dies. These clues are always GPS Evidence, but even so, they often fail to save the second victim.
  • Star Wars Legends:
    • In the book Isard's Revenge, Iella and Mirax examined a poisoned device that had been implanted in a man and had killed him. They went through computer programs to look up what planets had the facilities to make that sort of highly specific poison.
    • Also showed up in the original Rogue Squadron, with stormtrooper corpses from an attack on their temporary base turning out to have rashes caused by a specific minor illness from the Rachuk system, and analysing the DNA showed it to be a very recent strain.
  • In The Sum of All Fears, scientists are able to examine plutonium fragments left behind from a thermonuclear detonation and identify what reactor it came from. Which is an important clue, as everyone thought the Russians had exploded the bomb, but it had been made from American plutonium.

    Live-Action TV 
  • Arrow just loves this trope. Apparently it's super popular between villains in Starling/Star City to hide in abandoned factories that used to be dedicated to manufacturing an exclusive chemical formula that doesn't exist anywhere else in the world.
  • Abused mercilessly in Bones, usually resulting from a spore sample analyzed by Hodgins.
  • Occasionally used in Cadfael. Cadfael, the abbey apothecary, knows where and when every plant grows in the Shrewsbury area and has tracked down where people have been, evidence has been, and murders have taken place on the basis of what plant matter is caught up with them.
  • Subverted in one episode of Castle. The victims of the week both have traces of water containing diatoms (single-celled organisms). The forensic tech promises that they can identify the water source, and Castle and Beckett get her to test the water from a single fish tank. It's not it. Turns out, the water was from the harbor.
  • Columbo, more than once.
    • In "Caution: Murder Can Be Hazardous to Your Health", Columbo is able to destroy a killer's alibi thanks to the victim's dog. It was friendly and had a habit of scratching at car doors, and is missing a claw on one paw. The killer claims he had never been to the victim's house, yet as Columbo points out, his car door has the dog's distinct claw marks on it.
    • In "Columbo and the Murder of a Rock Star", Columbo figured out a killer had been in the area of a murder because mulberries, which grow in an area near where the victim lived, had fallen inside the killer's luxury car's hood.
    • In "Strange Bedfellows", a pivotal piece of evidence turned out to be a dead mouse—specifically, the mouse was found in a Los Angeles restaurant but it turned out to be a breed native to the mountains of Southern California but not the city.
  • Done several times on CSI and its spinoffs:
    • In CSI: Miami, the team discovered a missing child's location by traces of a plant found only in a specific area of the Everglades.
    • On CSI: NY a suspect was caught due to sand from a specific island in the Pacific which the suspect had imported to donate to a prestigious pre-school in order to increase the chances of his son getting in.
    • Subversion: CSI: NY played a long game with this trope in the fourth season. In the season's first few episodes, a lot of cases were solved using GPS Evidence. However, in "One Wedding And A Funeral," Stella finds tree bark at a crime scene. She locates the only furniture store in New York that uses wood from that tree, and lo and behold there's someone with a record who works there. But wait! He didn't do anything! The tree bark was actually a clue left by Mac's stalker, intended to lead him to the Tribune Tower in Chicago.
    • And of course the CSI season five finale, "Grave Danger," when Grissom, Entomologist Extraordinaire, determines Nick's location from the ants in his box since fire ants can only be found in wet fertile soil, which in the Nevada desert means plant nurseries; combining it with the known radius of how far Nick could have gone and the fact the kidnapper's relatives own one, they're able to pin down the spot to send the search and rescue.
    • CSI used this in a remarkably literal sense in the episode "Fracked." GPS data from a car and cell phone played important parts in the investigation of the title case.
  • DCI Banks: In "The Buried," a footprint left behind at the scene of a crime contains the mixture of the chemicals used in match heads. This leads the police to the only old match factory in the area.
  • The algae on the rocks Dexter used to weigh down his victims help the cops narrow down the list of suspects...
    • It helps in that case that they already had a small number of possible marinas to gather samples from and compare the evidence to. It was Dexter's conceit that he kept weighing bodies down using rocks from the marina where he keeps his boat.
  • Doctor Who: Used by the Ninth Doctor, of all people, in "World War Three." The Doctor gathers up everything the cast has learned about the Slitheen and is able to use the outer space equivalent of the trope to identify their home planet, thus their species, thus their Weaksauce Weakness.
    "Narrows it down!"
  • Subverted in an episode of Due South. Fraser figures out that a man involved in a case is a boxer by means of a Sherlock Scan. What makes him so certain that he trains in this particular gym? He was wearing a shirt with that gym's name and address on it.
  • Barry identifies the location of the villain's lair in the debut episode of The Flash (1990) by identifying several soil samples, and figuring out where they overlap.
  • The Fresh Prince of Bel-Air: Brit Geoffrey pinpoints exactly where in the UK his British date is from after hearing her accent. The only thing he guesses wrong is the floor of the building that she lived on — it's the second, not third.
  • Halo: Nightfall has Jamieson Locke and his fellow ONI operatives trying to determine the exact source of the primary substance used in a Covenant bioweapon that only affects humans. They are able to find out that it used a previously unrecorded heavy transuranium element that can only be found on a shard of the Halo ring that Master Chief destroyed in Halo: Combat Evolved.
  • Subverted in Inspector Morse, when an analyst realises where and when a photo was taken. Morse is positively impressed, and asks 'how on earth did you realise that?' (or something to that effect), only to hear the obvious response: 'it's written on the back'.
  • Jake and the Fatman: In "Rhapsody in Blue", Jake gets sticky sap stuck to the roof of his car when he visits the murder scene. Later, while talking to the garage attendant, the attendant sympathizes and says that he had to clean that sap off the car of one of the suspects twice within 24 hours. Jake realises that the suspect had returned to the scene of the crime after the legitimate visit he had told the police about.
  • Done on all versions of Law & Order. In particular, the UK version has them realizing that a victim was not killed where he was buried when their forensics expert reveals that the soil samples found on the sheet he was wrapped are from different locations. With this, the detectives realize that their chief witness — the killer's accomplice — is telling the truth.
  • Subverted in Legend of the Seeker by a clever villain. Richard, investigating a murder, finds residue from a certain type of plant on one suspect's clothing that implicates him in the murder. After the man is tried, found guilty, and executed, they find out that the real killer planted it as evidence, counting on Richard to find it.
  • MacGyver (1985): In "Walking Dead", Mac is able to identify that the cult is using an abandoned dam as their base from the mixture of dried river silt and machine oil on a voodoo doll.
  • Marvel Cinematic Universe:
    • The Defenders (2017): Danny Rand and Colleen Wing, trying to find leads on the Hand, face a setback when Elektra kills a man they have been tracking for months. The man says with his dying breath that the war with the Hand is in New York City. On returning to Manhattan, they determine that the sword the dead man was carrying must have been to an exclusive sword shop that is only located in Manhattan. They travel there and encounter Hand henchmen destroying bodies with acid, and Danny's attempt to rough up Cole for answers leads to him encountering Luke Cage (2016).
    • Daredevil (2015): Early in season 2, Matt locates Frank Castle's den and armory by following a blood trail left by a wounded dog he stole from the Kitchen Irish. As he's blind, he has to rely on the smell of the blood and his other senses in order to trace the route.
    • Jessica Jones (2015): Jessica has to rely on various takes on this trope to get clues for cases.
      • When Jessica realizes that Kilgrave has someone taking pictures of her, she initially tries to go to various spots around the city where these pictures have been taken, in order to pinpoint the photographer's position. While on another job, she sees an NYPD surveillance camera and realizes that maybe one of those cameras caught the spy. So she contacts Will Simpson and gives him times and dates from various cameras she's passed, so she can look and see if any faces show up following her in any of them.
      • To track down Kilgrave after he takes control of Luke, Jessica looks through news articles trying to find anything from people who mistook his powers for performance art.
      • Early in season 2, after an encounter with the fake "Dr. Leslie Hansen" (actually Jessica's mom), Jessica realizes that the imposter was wearing a wig made of real human hair. Trish notes it's a pretty high-quality wig as she didn't catch it, and says there are only three wig shops in New York City that make wigs of that quality. The first one they hit (owned by a woman who made wigs for Trish during her It's Patsy days) recognizes the woman.
    • Loki (2021): The Kablooie gum the Variant left as an Anachronistic Clue was sold in a limited region for a short span of years, narrowing down the Variant's hiding place.
  • Monk:
    • In "Mr. Monk and the Three Pies", Adrian's brother Ambrose points out that of course Pat van Ranken's old pickup truck runs, and that it's been to a certain section of the park because it has yellow acorns in the truckbed that only grow in one spot in the park. Impressive knowledge of the local ecology, for a guy who never leaves his house.
    • Subverted in "Mr. Monk and the Genius": Monk realizes that one of the flowers in Patrick Kloster's yard is an oleander plant, and oleander sap can be used to create a poison that imitates the symptoms of a heart attack. He takes it to Stottlemeyer as his primary evidence... only to be immediately shot down because of how common it is.
    • Subverted (and possibly parodied) in "Mr. Monk and the Other Detective". Marty Eels, a private investigator who has a loser's reputation, shows up at a jewelry store robbery with all the answers. When the store manager's car is found abandoned on a back road, Marty finds a mosquito on the floor of the car and is able to recognize its species and genus and whatever and point out that it only appears in this one particular place in the city that the body is at. Monk and Natalie eventually determine that he had been faking it and knew where the body was the whole time, as his mother, a quality control operator, had overheard the killers bragging about their crime while on hold to buy plane tickets to flee the country, and told Marty all of the information rather than call the police and turn the guys in.
    • Done in a Show Within a Show of "Mr. Monk and the TV Star". The CSI rip-off Crime Scene S.F. has a fictional device being used to analyze a fiber that is immediately traced to Colombia and a certain drug cartel that appears to be a recurring villain on the show. Monk is incredulous that people believe that crap. Meanwhile, his police friends don't care, even though they obviously know better, as they're happy to be consultants on the show.
  • My Life Is Murder: In "Feet of Clay", Alexa identifies the killer, and then is able to provide the evidence the police need because of the dirt and leaf litter trapped in the killer's shoes that could only have been picked up at the murder scene.
  • Parodied in Police Squad! when Lieutenant Drebin gets a rock thrown through his window. He asks the forensics lab to find out where the rock came from and gets a geology lesson in response. Later on, Drebin confronts the thug who threw the rock, who starts giving the exact same geology lesson.
  • NCIS has done this a number of times. Examples include:
    • In one episode, the team placed a suspect at the scene of a crime because Abby found silica dioxide and calcium oxide in his shoes. Basically, they found sand and lime, one incredibly, and one reasonably, common substance, and arrested him on that. It helped that they already suspected him, and there was a glass-making company next door to the crime scene, however.
    • There was the time Abby tracked Reynosa's movements by tracking bug bites on her dead smuggler's skin... In a matter of hours...
    • In the second-season episode "The Good Wives Club", the team got pointed in the right direction when Abby found bits of beetle exoskeleton at a crime scene in Norfolk - a species of beetle that only lives in a small region of Florida.
    • In "My Other Left Foot", a seed found on the boot of a dead Marine gets linked to a tree near the suspect's house. More justified than many examples, since individual plants can in fact be identified by their DNA just like humans (or any other organism) can.
    • In "Agent Afloat", the team knew to look for a suspect from American Samoa after Abby found traces of a flu virus on a murder victim, and identified it as a strain unique to Samoa.
  • Rizzoli & Isles:
    • Maura finds a killer by tracking the poison to a flower native to Boston. Of course, the suspect has said flower growing in front of their house.
    • Maura does a spectroscopy on a hair left by the killer, which somehow can tell what type of food the hair-bearer ate. This hair was from someone who had recently eaten fermented whale meat, a common dish in Scandinavia. Turns out the victim's assistant had just gotten back from Iceland.
  • Used in almost every episode of Sherlock although when the eponymous character does it, he normally uses a variety of clues. He makes basically a Venn Diagram of clues, each one corresponding to a few locations, and then sees which location fits them all.
    • Played with in "The Blind Banker", where Sherlock meets an acquaintance from the university and tells him that he knows he has recently flown around the world twice. The guy asks if it was some sort of stain from tea that only comes from India. Sherlock calmly replies that he spoke with the guy's secretary. After the meeting, John confronts him about it, as he was there and didn't see Sherlock speaking with the secretary. Sherlock admits that he just wanted to put the guy down and really got the clue from the guy's watch which is two days off.
  • On Star Trek: Deep Space Nine Dr. Bashir's James Bond holodeck program invokes this trope. He sees a ruby and is able to narrow its origin down to a small geographic area based on what shade of red it is (the redness is directly proportionate to the concentration of chromium ions).
  • Stranger Things:
    • One of the plot hooks in Season 3 is a strange communication in Russian that Dustin's radio picked up. Steve realises that the call must have been sent from Hawkins, rather than to it, because the music in the background is the same as that played by the kid's amusement facilities in the mall.
  • Subverted in an episode of Top Gear: The boys are having their used cars examined at a forensics lab to see how their previous owners had treated them. At one point, James tells Jeremy that the techs had discovered that his car had belonged to a Muslim man in Birmingham. Jeremy and Richard are amazed that they were able to find that out just by "squabbing the seats" until James elaborates that they had found a letter from a mosque in Birmingham in the glove box. Here's the clip.
  • Played with in an episode of A Touch of Frost involved a suspect in a murder whose trainers had been determined to have fragments of glass embedded in the soles. DI Frost then went on to point out to the suspect that Forensics could match the composition of the glass fragments to a specific manufacturer, namely a local glassware firm with a skip full of quality-control rejects quite near where the body had been found. Even if it really is possible to identify the origin of glass fragments that closely this isn't exactly the most damning evidence imaginable, and Frost was merely using it for Perp Sweating value.
  • Season 2 of The Wire revolves around the case of the dead women in a shipping container. While McNulty uses his detective skills — and the help of tide charts and a mining engineer — to prove the deaths happened within the juristiction of the Baltimore Police Department, it's less to do with solving the case than to spite his old boss. The investigation into the girls shows they come from Eastern Europe, and many of them recieved breast implants at the same clinic in Budapest, Hungary, but ultimately the leads go cold and despite his efforts, McNulty fails at his attempt to find the name of the first girl he pulled out the water.

  • In Pygmalion, Henry Higgins can determine a Londoner's address down to the street name by his accent alone. The musical adaptation, My Fair Lady downplays it a bit, with Higgins only claiming a precision of "within three streets", and then only for some parts of London.

    Video Games 
  • Ace Attorney:
    • Featured in one case when it's necessary to locate a kidnapped spirit medium. The medium channels a spirit that takes note of the surroundings, and is then channeled by another medium to relay the information. Averted in that the clues are vague and not especially useful.
    • There's also the stuffed bear, which turns out to be really, really rare. Also averted in that Gumshoe tries this trick with the electrical equipment but it doesn't work because you could get that equipment from just about any shop.
  • In the Deadshot sidequest of Batman: Arkham City, Batman finds one of these at the site of the second and third Deadshot killings. Neither of these is useful by itself (Each individually can be found in dozens of places around Arkham City), but there are only three places where both of the items he found trace samples of can be located, which narrows the search area down enough that he can start investigating.
  • This is the point of the Police Officer's story in Heavy Rain. Once the evidence is found, the culprit can be tracked. Final evidence? Figure out the general area, then narrow things down with the evidence you've collected: the location of the owners of a particular type of car, for example, and the flower shops that sell a particular type of flower. At first, the area starts very large, but each piece of evidence narrows it down until finally, you have the last bit of evidence: a particular type of watch specifically given to police officers on their 20th year of service. And in the area you've narrowed down, there's only one police officer who's received that watch...
  • Defied by Futaba in Persona 5 Strikers regarding a machine she built to spread their calling card targeted at the Monarch of the Osaka Jail. She's asked afterwards if this will bite them later, but Futaba reassures her team that the machine was entirely built with local junk so the police won't be able to track them outside of Osaka.
  • Parodied in Vampire: The Masquerade - Bloodlines, in which Adventurer Archaeologist Beckett pinpoints the local headquarters of a secret society of vampire hunters by simply examining the hue and texture of a pinch of beach sand, the distinct yet subtle aroma of a whiff of incense, and the testimony of a vampire hunter dangled over a balcony by his ankle.

    Web Comics 
  • In A Miracle of Science, the police use isotope ratios to track which planet the raw materials for the bad guy's robots were mined on. He anticipated this. This sort of analysis is real science, usually used for classifying meteorites.
  • Parodied in this Shortpacked! strip. One has to wonder why villains don't do this more often.
  • xkcd: Parodied by "Science Montage," which contrasts a "Movie Science Montage" (lots of lasers and test tubes) with an "Actual Science Montage" (lots of waiting for a centrifuge). The strip provides the page image.
    Movie Scientist #1: Paint flecks from the killer's clothing match an antimatter factory in Belgrade!
    Movie Scientist #2: Let's go!
    Actual Scientist #1: Okay, we've determined there's neither barium nor radium in this sample.
    Actual Scientist #2: Probably.

    Western Animation 
  • Batman: The Animated Series:
    • One episode made this a little more justifiable: Batman still took a random mud sample, but rather than discovering an obscure location from which it came, he instead discovered that it was part of Clayface... and he's unique.
    • In another episode, Batman is able to figure out where Robin's kidnappers have taken him based on the photo of him they left behind as evidence of their action. He recognizes the unique knife type and rope-making technique to a very specific area of the world. Justified as this is a test of skill fabricated by Ra's Al Ghul to evaluate Batman's detective abilities.
  • The Batman's version of Bruce Wayne was also shown occasionally dabbling in this, including tracking down a kidnapped Ethan Bennett to a carnival hideout of the Joker's.
  • Subverted in Chip 'n Dale: Rescue Rangers. Gadget performs some chemical tests on a flyer from a travel agency which is the villain's lair, and then she tells her friends the exact address. She read it on the flyer.
  • Darkwing Duck:
  • Done twice in Kim Possible, first with a rare plant that grows only around one specific waterfall, and again with a rare dog breed that comes from only one breeder in the whole world.
  • Played straight in the episode of Phineas and Ferb where Carl is briefly turned evil by Dr. Doofenshmirtz. Carl is trying to find Perry the Platypus as part of his evil plan and is able to narrow down his location based on an extremely rare flower he sees in the background of Perry's video communicator which only grows in one spot on the entire continent of Africa.
  • Spider-Man: The Animated Series - When Spider-Man mutates into a bestial "Man-Spider", a post-Heel–Face Turn Kraven the Hunter uses this to track down his lair.
    The Punisher: Huh. World Trade Centre parking garage. How did you know?
    Kraven: The gravel that I found in Man-Spider's webbing. It still had the scent of gunpowder from that bomb explosion of years ago.
  • Star Wars: The Clone Wars: In "Blue Shadow Virus", a bug is used to pinpoint a hidden Separatist base to a specific part of Naboo.
  • In the Sushi Pack episode "But Is It Art?", while investigating a recent art theft, Kani finds a small piece of granite found only in one region along the coastal mountains. Which she identifies as such on sight.
  • In the Teenage Mutant Ninja Turtles (1987) episode "Case of the Hot Kimono", April's famous detective aunt traced a very rare olive oil only found in one island and the only place where it's shipped to.
  • In one episode of Totally Spies! a villain is tracked down by an unusual shoe print at a crime scene that matches a rare shoe that only three people in the world own. The first, a female basketball player, is crossed off because the spies had seen the perp from a distance and identified him as male. When Jerry continues by identifying a clown as the second buyer, he and the girls just share a glance over the communicator before he brings up a scientist as the last one and gives them the address to investigate.
  • Done a few times on Where on Earth Is Carmen Sandiego? (the 1990s cartoon). In these cases, they had a bit more credibility, as the clues were often intentional hints left by Carmen for the detectives, and were usually significant enough culturally or historically to be useful: for instance, the idea that Komodo dragons are found on only one island in Indonesia.

    Real Life 
  • In a real-life case profiled on some True Crime show years ago, a killer backed his vehicle into a tree while fleeing the scene. Some seed pods were found in the bed of the suspect's truck. The police managed to DNA match the bean pods to that specific tree. This is an example of how this type of evidence is usually used, to confirm or reinforce a connection that is already known.
    • Most likely the program was The New Detectives: Case Studies in Forensic Science. The show mentions forensic applications of botany and entomology in different episodes. E.g., chiggers were the clincher in one case, being found in only one place in an entire county - the exact place a murderer chose to dump the body of his victim.
    • And quite a few times, the police have been able to prove that someone was in a kidnapper's or murderer's car by matching fibers — either fibers and/or DNA from the body that match those found in the suspect's car or fibers in the car that match clothing worn by the suspect (or both), or fibers found in the interior (either in the back seat area or trunk) that connect to the suspect in some other way. A surprisingly (somewhat) common example is being able to (microscopically) match animal hairs found in the suspect's vehicle to those found on the kidnap/murder victim's pet, particularly if they had a pet dog.
      • This has actually been inverted with the advent of DNA evidence becoming practical - a few old court cases that resulted in convictions (and imprisonment, and in some cases a death sentence) have been overturned because the GPS Evidence excluded the accused, proving their innocence.
  • According to The Other Wiki, during World War II sand used in the ballast of Japanese fire balloons was used to determine not only that they were not launched from within the United States, but also which Japanese beaches the sand was taken from.
  • Intelligence agents had attempted to locate Osama bin Laden by analysing the background in his videos. They actually succeeded during the Afghan war. However, the Geologist consulted didn't keep his mouth shut, and from then on any tapes smuggled out carefully concealed any background geology.
    • This is why putting yourself in front of a green screen or a similar sort of background-blocking screen is recommended when doing live streaming at home or some other private place. Streamers have been doxxed, swatted, and had various forms of harassment come to them in real life because people have been able to track down where they were based on the layout of their home or something else in the background.
  • The kidnapping/murder of Bobby Franks, committed by Nathan Leopold and Richard Loeb, was solved as police found a pair of eyeglasses with an unusual hinge design at the crime scene next to the body. A design so unusual that only three had been sold in the area, one of which was to Leopold, the younger of the killers. Even worse for Leopold, the police easily dismissed the other two owners as suspects: one was able to show his glasses to the police when they came to question him, and the other guy had been out of town when the murder happened. Leopold tried to dismiss it by saying he dropped them while in the area studying bugs, but this admission proved to be GPS evidence in itself since it tied him to the location where the body was dumped in the first place.
  • One bit of an episode of the docu-series Extreme Forensics had investigators trying to bust a guy's alibi that he was in Ohio with his brother, while he was murdering his wife in Bakersfield, California. Desperate, because the rental car he had been driving had been washed of much evidence, they turned to trying to identify bug bits that had been caught in the radiator and found a grasshopper leg that was unique to a species in the Sierra Nevada region. Subverted: it didn't break the case but it did show he was lying about where he was.
  • Commonly used for investigating bombings or hit-and-runs. Explosives, plastics, and paint have unique markers that let forensic teams figure where they probably came from, even from incredibly small samples. The same goes with the red dye packs used to track bank robbers.
  • William Buckland (1784 - 1856) is said to have been able to tell during wanderings where exactly he was, just by examining the rocks around him. Not that surprising if you consider that the man was one of the most important geologists (and paleontologists) of his time.
  • "Forensic Astronomy" uses the position of the stars to figure out the EXACT time the photo was taken. While it is usually used to, for example, figure out when noted Ansel Adams photos were taken or when a painting was done, there's no reason why it couldn't also be used for photographic evidence in criminal investigations (such as when the last photo taken of a murdered person alive was, if the date on the digital camera is incorrect).
  • The documentary Sherlock Holmes: The True Story re-enacts Dr. Joseph Bell telling his class of students that the volunteer arrived through a certain path, based on the reddish-marks on the shoes. Sir Arthur Conan Doyle was inspired by this, and let his Sherlock Holmes character perform the same feat as well.
  • The cast of "Adam", a boy whose headless torso was found in the Thames. Forensics was able to determine that he was from Nigeria from the contents of his stomach but never found the killer.
  • One general example that really is quite specific is isotope analysis. By taking a person's hair samples, it is possible to determine where they have been recently based on the water they have been drinking. The obvious solution to beating this is to only drink bottled water or shave your head. Though either of those would be somewhat suspicious in and of itself in most cases.
    • The same general techniques also have been used to analyze drug samples.
  • In the 1960 Graeme Thorne kidnapping/homicide case, the body was found with fibers from two different species of cypress and traces of a pink limestone mortar. The police asked postmen if they knew of a house like that and narrowed it down to the killer's house. It is considered a landmark case in Australian police forensics.
  • The userbase of 4chan is infamous for its ability to coordinate and track down individuals & locations using this, to the point of being Scarily Competent Trackers.
    • In the earlier days of the My Little Pony: Friendship Is Magic fandom, a troll started a coordinated bullying campaign against the author of Ask Princess Molestia, and later fans of the show in general for "not being 'proper' fans like she was". When said campaign went too far, and one of its followers attempted to have a naturalized citizen deported in response to his wife criticizing said campaignnote , 4Chan retaliated by doxxing the troll who started it by using photos on her blog to narrow down the city she was in and then comparing selfies she took in her backyard to images taken from Google Satellite to geolocate her home address and post it online.
    • The most famous instance being Shia LaBeouf's "He Will Not Divide Us" livestream, in which he raised a flag in protest leading to the most elaborate game of "Capture the Flag" known to man. At one point he attempted to hide it by filming the flag from below with nothing but the sky in view, but 4chan trolls managed to locate the flag in under two days by using astronomy, time zones, and detective work with airline flight paths. When he moved it to a deserted cabin, they found it by examining the wood pattern on the walls. The final location was in front of a blank white wall, which they tracked down to a house in London within four hours by examining how a light from off-screen shifted and eventually dimmed.
    • On another occasion, 4chan users managed to pin down the coordinates of a terrorist training camp in southern Aleppo, Syria and coordinated with a Russian journalist to successfully arrange an airstrike on the location using a combination of Google Maps and footage from one of their own recruitment videos.
  • Professor Christian Gottfried Ehrenberg provides what is quite probably the Ur-Example of this trope being used to solve a real-world major crime- A barrel of silver coins being shipped by train across Prussia as part of a major monetary transfer was discovered to have had its contents replaced with rocks and dirt during transport, threatening to stir up an international incident as both sides accused the other of arranging for the shipment to be "lost". Stumped investigators had the bright idea to bring the barrel full of material to the geology department at the University of Berlin, where, by comparing the contents to samples from every station along the train's route, Prof. Ehrenberg was able to identify the exact station where the replacement had to have been made. The loot was soon thereafter recovered from a disgruntled railway worker at said station.
  • The group behind the July 2007 bomb attacks in London were caught partly thanks to a rather unlikely variant: The police couldn't find anything useful in the chemical residue left by the explosives themselves because they were homemade, but what they did eventually discover was that the explosive mixture was contained in plastic food containers that turned out to be a rather uncommon brand that was only sold by one wholesaler supplying a relatively small number of retailers. This was enough to narrow down the location of the address where the group prepared the devices to within a mile or so of one of those retailers, and a couple of reports of suspicious activity (people coming and going at odd hours, a strong chemical smell coming from an apartment) did the rest.
  • GeoGuessr puts the player in the position of deducing their location only from a 360 degree Google streetview shot. Skilled players say they can identify locations based on foliage and soil color.


Video Example(s):


What Do You See?

Shan-Yu and his Huns manage to deduce that the Chinese Imperial Army is staking out at a village within the mountains that is situated between them and the Imperial Capital.

How well does it match the trope?

4.68 (19 votes)

Example of:

Main / SherlockScan

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