"I see you found the crumb. I knew you wouldn't notice the enormous flag."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.
— Negaduck, Darkwing Duck, "Just Us Justice Ducks, Part 1"
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Anime & Manga
- Used a couple of times in JoJo's Bizarre Adventure part 3. 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.
- 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.
Films — Animation
- 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 sulfur from cannons — that tells him the location of the village and that the Imperial Army are there.
Films — Live-Action
- 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 the first Charlie's Angels film, 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 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.
- 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?
- 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 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.
- 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.
- The two 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.
- 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.
- 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.
- 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.
- 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.
- Star Wars Expanded Universe:
- 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.
- 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 remember's 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".
- In 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 in the same book, though: 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.
- 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.
- 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.
- 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.
- Done several times on CSI and its respective 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 kidnaper'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.
- 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 proportunate to the concentration of chromium ions).
- Abused mercilessly in Bones, usually resulting from a spore sample analyzed by Hodgins.
- Columbo, more than once. Columbo once figured out a killer had been in the area of a murder because mulberries had fallen inside the killer's luxury car's hood.
- 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'.
- 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.
- NCIS has done this, placing a suspect at the scene of a crime because they 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.
- And once they placed someone at a crime scene by testing the plant DNA of the burrs found on his shoes.
- There was the time Abby tracks Reynosa's movements by tracking bug bites on her dead smuggler's skin... In a matter of hours...
- 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 bad luck that he kept weighing bodies down using rocks from the marina where he keeps his boat.
- 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.
- 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.
- 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.
- 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.
- 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 tell him that he knows he has recently flew 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.
- 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.
- Used by the Ninth Doctor, of all people, in the Doctor Who episode "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 GPS Evidence to identify their home planet, thus their species, thus their Weaksauce Weakness.
- 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.
- 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.
- MacGyver: 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.
- 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.
- 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.
- 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.
- 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.
- 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 manufacture an exclusive chemical formula that doesn't exist anywhere else in the world.
- In Pygmalion, Henry Higgins can determine a Londoner's address down to the street name by his accent alone.
- Ace Attorney:
- Featured in one case when it's necessary to locate a kidnapped spirit medium. The medium channels a spirit who 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.
- 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.
- 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...
- 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.
- xkcd: Parodied by "Science Montage".
- Parodied in this Shortpacked! strip. One has to wonder why villains don't do this more often.
- 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.
- Lampshaded in an episode of WordGirl.
- 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:
- In "Just Us Justice Ducks, Part 1", Darkwing deduces the location of Negaduck's hideout from a single crumb — completely failing to notice the enormous Negaduck flag on the roof. As the page quote says, Negaduck planted the crumb there on purpose because he knew Darkwing wouldn't notice the flag.
- In "In Like Blunt", Darkwing presents a grain of sand as their only clue to a case. All of his chemical tests can only reveal that it is indeed a grain of sand, so the James Bond-Ersatz tastes it and says that it could only have come from one of several hundred islands... but only one didn't have a plant that the villain was deathly allergic to growing there indigenously.
- 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.
- 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.
- One episode of Batman: The Animated Series 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.
- In the 1987 Teenage Mutant Ninja Turtles 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 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 episode of Star Wars: The Clone Wars "Blue Shadow Virus", a bug is used to pinpoint a separatist base to a specific part of Naboo.
- 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.
- The kidnapping/murder committed by Leopold and Loeb was linked to the perpetrators largely due to a pair of eyeglasses with an unusual hinge design found near the body, of which only three were sold in the area.
- Even worse for them, the other two owners were very easy to clear 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. Talk about bad luck.
- One bit of an episode of the docu-series Extreme Forensics had investigators trying to bust a guy's alibi that he was in the Midwest with family while he was allegedly murdering his wife in 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 Siera-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 te Graeme Thorne kidnapping/homicide case two sorts of cypress and a pink substance indentified as limestone mortar. The police asked postmen if they knew of a house like that and narrowed it down to the killer's house. It was the first time Australian police used many forenics techniques.