Criminal Mind Games

The detectives are on the heels of a very unbalanced criminal who has left them a trail of clues to follow -- usually a test of their intellect, or their investigatory skills, as though the criminal wants to see if the detectives are worthy of catching him. Not only do the detectives oblige the nutter and follow his breadcrumb trail, they tend to give up all conventional routes of investigation. Usually they are the minutest step behind their quarry right until the end. Sometimes the criminal wishes to distract or trap the detectives, sometimes they want them to uncover some other truth along the way, but usually they're just being a real smartass. Sometimes the clues are hidden in the Serial Killer's Calling Card or in its gruesome souvenirs.

These people often enjoy wordplay. Anagrams abound, as well as sentences with a carefully designed second meaning, and proper nouns which are conveniently also real words ("wait a minute, does he mean Jim Trashcompacter?").

See also Linked-List Clue Methodology for a number of non-(or at least less) criminal scavenger hunts. Compare The Walrus Was Paul.

Anime and Manga

 * Detective Conan:
 * A number of episodes of (especially the longer TV specials) involve some criminal leaving a trail of clues—either because they secretly want to be caught and stopped, or because they're just Ax Crazy. For whatever reason, many of these seem to involve bombs.
 * One TV special had Conan and Heiji running all over a baseball stadium to try to catch a would-be stadium bomber who sent them clues via abandoned mobile phones with a specific time limit to find the next one.
 * "Trembling Metropolitan Police Headquarters: 12 Million Hostages" involved a mad bomber who sent a clue to his next target to the timer screen of his current bomb…seconds before its detonation.
 * A long manga story set in London had a bomber leaving a trail of Sherlock-Holmes-themed clues all over London for Conan to chase down in order to stop his next bombing.
 * Subverted in Death Note: the master detective L expects Kira to be leaving messages -- but Kira is just as smart as he is, so only leaves red herrings to throw L off the scent, or meaningless clues to waste his time.

Comic Books

 * In all incarnations of Batman, this is The Riddler's modus operandi; other Batman villains, notably The Joker, have also done it.
 * Lampshaded during a Villain Team-Up that takes place in one of the old 1960s Batman movies, where the Riddler's colleagues eventually grow tired of him compromising their plans by leaving clues that they know Bats will inevitably solve. They try to stop him from doing so, but he fervently declares that he just can't resist and proceeds to leave more clues that eventually lead to their defeat.
 * Interestingly, an early Batman story showed that the Riddler's insanity is such that he is physically incapable of committing a crime unless he leaves a clue. (His father used to beat him when he lied... so once dear old Dad was out of the way and only the consequential neuroses were left, he learned to tell the truth in extremely sneaky ways to get around them.)
 * One comic set in The DCAU had Batman fail to decypher the Riddler's clues; he stumbled upon the crime because he was following three other crooks who had the same target. When the Riddler realises this, he doesn't care that he's going to jail because as far as he's concerned, he won.
 * Subverted by another Batman villain, the Cluemaster, a bargain-bin Riddler type with a similar modus operandi. The Cluemaster was caught thanks to his own clues and went to prison, an experience which cured him - of leaving clues. Once free, he resumed his criminal activities without bothering to leave clues any more. As Robin says, "Gee, thanks Arkham!"
 * In his first re-appearance, the Cluemaster had hired some goons who, knowing their boss's old M.O., left clues behind anyway. And being stupid goons, the clues were really obvious, too.
 * Unfortunately for him, his daughter, Stephanie Brown, was angry at him for trying this while claiming to be reformed, and became, leaving clues to her father's crimes for Batman. She later became one of the Robins herself. And then she died. Kinda.
 * So that's what the hell her name means.
 * Issue #6 of Untold Tales of Spider Man had Spidey and the Human Torch working together to stop The Wizard, who left logic-based puzzles as clues to his next caper. The crime spree was The Wizard's attempt to prove that he was smarter than the Torch, but Genius Bruiser Teen Genius Spider-Man solved them all fairly easily.

Film

 * Se7en,.
 * In the movie I Robot, the does this, the initial clue being, ostensibly to reveal his secret to the hero without tipping off a  in time to prevent a . (Yeah, the movie did something clever and subversive. )
 * The movie In the Line of Fire.
 * Averted in The Watcher. Oh sure, the Serial Killer would like to get the detective to play a game with him, but the detective doesn't care
 * V was this in V for Vendetta to the inspectors (Nose, not Finger). He actually used the term, but in a more insulting/literal reference to Creedy.
 * The Abominable Dr. Phibes accidentally dropped a medallion with some Hebrew lettering at the scene of one of his crimes, which tipped the police off to the Old Testament theme of his serial killing.
 * In Beverly Hills Cop 2, this is the Big Bad's apparent modus operandi, by leaving so-called "alphabet clues" at the scene of each of his daring crimes. It turns out to be a Subversion, as the clues are designed to distract the By The Book Cops' attention and set up a Red Herring scapegoat while the real mastermind escapes.
 * Jigsaw does this in Saw 2, having abducted a Detective Matthews' son and left him, and numerous other victims-including Amanda, a survivor of his games- in a house filled with death traps, and is recording the whole thing, which becomes useful when the detective and a SWAT team show up to arrest him. Jigsaw says the son will be returned alive and safe if Matthews just has a conversation with him, but the house is also filling with nerve gas that will kill everyone inside in two hours..

Literature

 * The James Patterson novel and movie Along Came a Spider.
 * Sherlock Holmes himself had to deal with his share of these villains, making this Older Than Radio.
 * This seems to be particularly common for movie and video game versions of Holmes, and less so in the Canon. In particular, he's been sent on scavenger hunts through famous sites in London by thieves twice, at least -- in the Infocom text adventure The Riddle of the Crown Jewels, and in the more recent Sherlock Holmes: Nemesis. Ironically, Moriarty is the villain and riddler of the former, not the latter.
 * Hercule Poirot came up against a Criminal Mind Games villain in The ABC Murders, where the killer sent him mocking letters before each of the murders.
 * Double-subverted in John Buchan's Richard Hannay novel The Three Hostages. The villain leaves a riddle for the police, in the form of a six-line poem. Subversion: It's deliberately uncrackable, and therefore should act only as a distraction. Double-subversion: But, possibly subconsciously, he laces the riddle with subtle clues, which the heroes crack thanks to a number of remarkably fortuitous encounters and observations.
 * In Blood Work, the "Code Killer" leaves the number sequence "903 472 568" at his crime scenes as a taunting hint. The solution?
 * G. K. Chesterton's very first Father Brown mystery, The Blue Cross subverted this in two ways: first because the clues themselves were meaningless, and second that it wasn't the criminal leaving them.
 * 87th Precinct: This is the M.O. of recurring villain the Deaf Man in Ed McBain's novels. There is a slight aversion in that while the Deaf Man sends taunting clues to the police, they seldom fully decipher them and are more likely to stop his crimes by accident than design.
 * Used by Melisande in Kushiel's Chosen. She thinks of her attempt to gain control of Terre d'Ange as a game and Phedre as her Worthy Opponent, and so sends Phedre a hint to start her search.
 * Subverted in Jorge Luis Borges' Death and the Compass. Lonnrot thinks he's oh-so-clever for figuring out there'll be four cabalistic assassinations, not just three...
 * Played with in Red Dragon, where the police intercept a fan letter the Serial Killer sent to his idol, Hannibal Lecter. Lecter begins corresponding with him in the sensationalist newspaper The Tattler with a cryptic message, and as the FBI aren't able to decipher it in time they decided to let go ahead as it's their only means of contacting him, and when they finally deciphered it they could take Lecter's place. Unfortunately, it wasn't the Dragon they were playing mind games with - Lecter's message
 * Another Note: The entire book is about trying to solve a very, very, difficult one of these. The killer, Beyond Birthday, left several clues leading from one murder to the next. None of the investigating officers could even start to decipher B's clues. Only Naomi Misora -- under L's guidance -- and an "unprivate" detective named Ryuzaki could help. The clues lead Naomi Misora in person to find each and every one of these clues to make sure the effort didn't go to waste.

Live Action TV

 * Subverted in Homicide: Life On the Street in the episode "Sniper". A serial killer draws a hangman game in chalk at the scene of each crime, with another letter filled in each time. The detectives hope that if they can guess the word, they can solve the crime.
 * Law and Order Special Victims Unit: though the police didn't give up on traditional methods entirely. In fact, by using traditional methods, they're able to catch the perp before he can complete his intended killings, and even manage to save a victim without stooping to his level.
 * CSI: Occurs with vastly more complex clues than usual.
 * For starters, it happened with the following: Paul Millander (prop artist who enjoyed taunting Grissom), the Blue Paint Killer (likewise), Nicky's kidnapper at the end of Season 5 (who did it to prove a point), and the Miniature Killer (who only left clues because of an involuntary urge due to psychosis). Arguably, the Strip Strangler was amused at the police and FBI's feeble attempts at capture, but was meticulously neat and planted fake evidence rather than leave any.
 * Numb3rs: Usually the clues require advanced mathematics to unravel, since the show's Aesop is that Maths is useful and mathematicians are like superheroes -- with maths. "The Janus List" took this to ridiculous extremes. Supposedly, the whole point of the exercise was to give the FBI a list of double agents, but the character who had the list made it all but impossible for the FBI to find it.
 * Charmed: A group of demons perpetrates a series of attacks using an Alice in Wonderland theme. The justification is that the Charmed sisters have recently faked their own death, and the demons have a theory that they are still alive and won't be able to resist investigating murders if there's a fairytale theme to give it that extra captivating interest.
 * In the season 3 finale of Psych Shawn faces the Yin-Yang Killer, who only rarely resurfaces to screw with star cops -- by kidnapping a victim and leaving stopwatches and clues, with the victim dying when the star cop fails to solve the clues in time. When the Yin-Yang killer targets Shawn, Shawn gets caught up in the killer's clues, and  Eventually the killer is revealed to be
 * Also one of the rare straight uses of this trope that manages to be funny: Detective Lassiter thinks the Yin-Yang Killer is testing him, specifically. He is...wrong.
 * And then they do it all again the next season with Mr. Yang's partner, Mr. Yin.
 * MacGyver had an escaped criminal foe who went as far as to call him with math equations that would yield a clue when solved.
 * Variant: the Ghostwriter episode "A Crime of Two Cities." A cross-Atlantic trio of kidnappers is led by a nutty mastermind who insists that they commit their crimes (and communicate with each other) through trick sentences and anagrams, all of which mock their intended victim. Unlike the usual trope, the leader isn't testing the heroes. She's doing it because she's arrogant, and wants to show off how the heroes are incapable of figuring out her clever clues.
 * Captain Scarlet : The Mysterons do this all the time. The Mysterons; somehow, despite tipping their hand every single time, actually win in a few episodes, starting with the second.
 * Dexter.
 * Dexter himself does this to mislead the agents investigating his own murders. In a twist, his attempt to mislead actually helps the FBI agent to narrow down the investigation.
 * Subverted when The Ice Truck Killer sends clues to the police, but they're really meant only for Dexter.
 * Often done in The Pretender by Jarod to the Centre operatives chasing him both to mock them and to leave clues that their superiors were up to shenanigans behind their backs. Done more often in the first couple of seasons... later on, Jarod simply calls them to tip them off about their employer's latest wacky hijinx.
 * Criminal Minds has done this twice. In "The Fisher King", an unsub mostly just wanted to send them on a quest. Some of the team worked on it like a normal case, some of the team followed the breadcrumbs. The trail of breadcrumbs solved the case, and not following the rules nearly got one of the BAU killed. In "Masterpiece"
 * The unsub in "Unfinished Business" (who seems to be partly based on the Zodiac Killer, mentioned below) did this as well.
 * Actually, he was mostly based on the BTK killer Dennis Rader, who also left letters. The only Zodiac thing was that Rader's letters just taunted the police; he never left cryptic clues in them, though he would announce that he had chosen his next victim.
 * Bones did this with serial killer
 * One episode of Due South had this.
 * In Burn Notice, Gilroy leaves clues about his identity to Michael this way. To quote Television Without Pity, "either someone is setting up Mason Gilroy, or Mason Gilroy thinks he's the fucking Riddler."
 * Sherlock does this in the first season finale, "The Great Game." In a somewhat unique instance, the perpetrator is using unsolved cases as the bait for Sherlock, forcing him to dig up the truth so that his victims won't be killed.
 * Fox Mulder of The X-Files tends to get into these with reasonably human Monsters of the Week, such as Robert Modell a.k.a. "Pusher" from the eponymous episode, from "Grotesque", and  from "Kitsunegari".
 * The Murdoch Mysteries episode "Murdoch in Toyland", in which Murdoch is left a series of talking dolls designed to give him just enough clues to reach the next one, and also to make him overthink things and miss more blatant clues.

Music

 * The subject of Alice Cooper's Concept Album "Along Came a Spider".

Tabletop Games

 * In Exalted, Infernal Exalts are able to atone for their actions that displease their demonic masters by committing Acts of (Card-Carrying) Villainy. An example is "Best Enemy Recognition," in which the Infernal chooses a rival Exalt of roughly their same power level to be their Arch Enemy, and continuously attempts to draw the Exalt so designated into their life by such methods as sending them clues alerting them to their evil deeds.

Video Games

 * The final case of the DS game Unsolved Crimes is one big series of these.
 * The game Ripper, based on Jack the Ripper. But in the future!
 * Carmen Sandiego: Carmen is possibly only second to the Riddler in being known for this. She leaves the clues as a friendly challenge of wits against the Friendly Enemy / Worthy Opponent detectives.
 * Persona 4 has this with the Phantom Thief, who leaves clues for Naoto after stealing her items. This is a subversion in that the Phantom Thief turned out to be

Webcomics

 * Subverted in Irregular Webcomic: The heroes follow the hints, but get the wrong message.
 * Doubly subverted in that the place they're supposed to be going to is right next door.

Western Animation
"Bart: To find it, you'll have to decipher a series of clues, each more fiendish than... Lisa: Found it! Bart: Doh!"
 * The Simpsons
 * Chief Wiggum was the "Mutton-Chop Murderer", who wanted to create a crime even Lisa Simpson couldn't solve. Played as a parody, natch.
 * Subversion; Bart hides Lisa's report and challenges her with a series of riddles:

"If it is the sweets you seek, into the cloakroom you must sneak, and find where I keep my books, and hang my coat and bag on hooks. Behind the metal doors is stowed the sweets what make your head explode."
 * Spoofed in the South Park episode "Chickenlover": the titular animal molester always left a message at the scene of the crime. The clues turn out to be really, really obvious... but Officer Barbrady is illiterate, and thus, he can't read the messages. After forcing himself to painstakingly learn to read through children's books, he eventually manages to find and arrest the culprit... who turns out to be a bookmobile driver who was trying to encourage Officer Barbrady to confront his illiteracy, even though there was no way he could have known about it before he molested the first chicken.
 * Barbrady then celebrates his new found literacy by beginning to read books...starting with Atlas Shrugged, which he regarded as such utter garbage that he decided he would never read again, making the bookmobile drivers whole plan null and void.
 * Bromwell High: One of the girls hides some illegal sweets people are looking for and composes a rhyme telling where they are.

"Master Pho: I would have gotten away with it if it hadn't been for that meddling kid. Todd: Actually, you would have gotten away with it if you hadn't left us all those clues."
 * The animated version of Where On Earth Is Carmen Sandiego has this in every episode as a Shout-Out to Alphabet Soup Cans.
 * Subverted on Monkey Dust when a serial killer becomes entangled in a furious game of cat and mouse with a police detective. The thrill of the chase is blown when the serial killer accidentally falls asleep in his car at the crime scene after killing a man: blood stained and with weapon in hand. Disappointed that it ended with such an anticlimax, the police detective decides to let the killer go. Only to be then killed by him.
 * Lampshaded in The Replacements

Real Life

 * The Zodiac Killer; a serial killer who taunted California policemen with postcards and letters written in secret code. According to the letters he sent to the press, he killed people in order to have slaves in the afterlife. Ergo also his obvious stand-in Scorpio from Dirty Harry. A number of investigators and researchers consider many, if not all, of his "clues", including his codes, to be purely red herrings. He was never caught.
 * Jack the Ripper wrote letters to the police and newspapers, taunting them. The "From Hell" letter is the most infamous, as it was delivered along with part of one of the victims' kidneys.
 * Others who sent letters (some of them more coherent than others) include Son of Sam, BTK, and the Axeman of New Orleans. Usually, the capture had little to do with the any attempted mind games: Son of Sam was captured when a witness saw him loitering suspiciously near his illegally parked car around the time of the shootings then confessed quickly. BTK was caught after a floppy disk he sent was traced to a computer registered by a local church.