On the 15 (and a half) Types of Impossible Crimes

There’s been no end to the ingenuity of the impossible crime genre. When you see murders committed inside of perfectly sealed rooms, and stabbings in virgin snow where the killers leave no footprints, you’re only taking the daintiest of baby-steps down the iceberg of magic murders. Take a few steps further and you’ll find yourself barreling into the realms of animated murderous snowmen, disappearing hotel rooms, witchery, teleportation, telekinesis, premonitory dreams, apparitions, flying men, transmogrification, impossible golf shots, men dying from falls when there’s no elevated surfaces for miles, time travel, people running through solid brick walls, and even the apparently magical disintegration of a man in front of witnesses. All of which, mind you, must be explained through perfectly human means without reliance on far-fetched science-fiction technology or preternatural agency — or, if sci-fi tech and ghostly happenings are commonplace in your world, their rules must still be adhered (and are usually exploited to establish the impossibility…). A whole world of man-made miraculous murders that would have the skeptics of our world taken aback! When you imagine the impossible crime problem, you imagine a scenario which absolutely cannot be taken at face value, and which the characters in the story have to battle with the reality of, whether it’s through disproving the supernatural or an ostensible suicide. There’s an impossible crime tale for damn near every insane scenario under the sun a person could think of.

…Or so I said in On a Defense of the Impossible Alibi Problem. A perfectly good introductory paragraph, wasted.

The impossible crime tale seems to be a favorite of people looking to create taxonomies. From solutions to situations, the impossible crime sub-genre more than any other seems to invite people to create lists trying to chronicle every little manner of plot, style, and form that exists. You might argue that this is a testament to the sheer formulaicity of the impossible crime story, or a testament to the magnetism of its versatility…

Just like I’ve done before in attempting to produce a list of 50 solutions to the 3 principle impossible crime genres, I will here be attempting to produce a list of all every conceivable manner of impossible crime situation — within reason. I will only be adding to this list if I feel like the entry is all of (a.) something that meaningfully alters the presentation of the impossible crime, (b.) something that meaningfully alters the potential explanations to the crime, and (c.) categorically non-specific so to be applicable to a suitable variety of stories. This is primarily because the minutiae distinguishing two locked-room mystery situations is a lot less significant than the minutiae distinguishing two solution types — this also means I can provide less “theoretical” entries than I could before.

Over at The Invisible Event, Jim Noy has actually covered a lot of our bases on his own post a few years back on the same topic. My intention here is not to contradict him, but rather to supplement his list with a few potential entries I feel worth pointing out. I will be covering a lot of re-tread ground here, so in the interest of keeping Jim’s contributions and my own separated I’ll simply be listing Jim’s entries first in one set and then mine at the end. I’ll be supplementing each category with a paragraph or two explaining the concept too — just so that this is my post, and nobody else’s!

Without further ado…


1.) The Locked-Room Mystery

The grandfather of mystery fiction and the perennial favorite of all impossible crime aficionados, locked-room mysteries scarce warrant an introduction. You have a murder committed within a room locked, sealed, and barred from the inside so that every entry is blocked-off. The only key to the room is inside of the victim’s pocket, so the killer must be still inside of the room… and yet they are not! The implication is that the killer has someone walked through the walls or vanished into thin-air…

This is the most popular form of impossible crime, and examples are a-plenty. Edgar Allan Poe’s “Murders in the Rue Morgue”, popularly (and debatably) considered the original detective story, Clayton Rawson’s Death from a Top Hat, and John Dickson Carr’s The Hollow Man (also known as The Three Coffins) all features killers who seem to vanish into mid-air within a locked room…

1.5.) The Judas Window Locked-Room

Not, perhaps, a separate situation altogether, but a prominent enough sub-sub-subgenre to warrant mention, this is one of those “Doylist Impossibilities” I invoke in On a Defense of the Impossible Alibi Problem. The situation is entirely the same as a traditional locked-room mystery, with one caveat: there is a single suspect locked inside of the room with the victim, so that it appears entirely impossible for them to be innocent of the murder! The situation is only impossible if you, as the reader accept the condition that this person is innocent and the murder must’ve been committed by an external agency.

I’ve named this one after the most prominent example, John Dickson Carr’s The Judas Window. This situation is a favorite of many cases of the Phoenix Wright: Ace Attorney video game series in which you defend clients falsely accused of murder — more often than not, this accusation comes as a direct consequence of the defendant being locked in the same room or sealed in the same general location as the victim. Edward D. Hoch, the “Master of Short Stories”, also produced more than a handful of these, such as “A Shower of Daggers”.

2.) Footprints in the Snow

…or sand, or dust. These crimes involve a man found murdered in a vast expanse of snow! The killer definitely murdered the man from close-quarters, and the man was murdered after the snow had finished falling… so how could the killer have committed this murder without leaving his footprints in the snow!? A killer who can somehow float over the snow…

John Dickson Carr dealt with the problem most notably in The White Priory Murders, and his French-speaking disciple Paul Halter also wrote these in, among others, The Lord of Misrule and The Gold Watch. Christianna Brand produced one of these in Suddenly at his Residence using dust, and Arthur Porges’s “No Killer has Wings” and Hal White’s “Murder at an Island Mansion” are two examples of this problem on sandy beaches.

3.) Psychological Impossibility

We’re starting to get into the abstract. A man’s death is caused not by direct murder, but instead by a behavior that is so absurdly unbelievable it defies every known principle of human psychology! The most famous example of this is Father Ronald Knox’s “Solved by Inspection”, which involves a man who starves to death in a room surrounded entirely by safe-to-eat food that he could’ve eaten at any moment.

4.) Impossible Physical Feats

Humans are constantly displaying their infinite capacity for improvement. Records are always being broken, and the human condition forever expanding. But in these stories, these feats of athleticism swerve from the superhuman straight into the supernatural. A man cannot run from California to New York in a matter of hours, neither can a man leap from the top of the Eifel Tower and land with not a single scratch on his body…

The Stingaree Murders by W. Shepard Pleasants features a knife that’s hammered into the wooden boards of a boat so tightly that not even Mike Tyson himself could remove it without causing significant damage and creating noise that would assuredly not go unnoticed — naturally, the knife is removed. Death in the Dark by Stacey Bishop tells of a baffling murder in which a killer is somehow able to make an eagle-eyed shot at his victim in pitch-black darkness! Impossible Bliss by Lee Sheldon involves a nearly-impossible perfect golf shot from a nearly-impossible angle that not even the most seasoned of pros could achieve!

5.) Killer Rooms

Without fail, every single time a man sleeps in the bed in room 405 of the Dickson Inn, he never wakes up… and is found the next morning, having died of heart failure at precisely midnight… The killer room involves spaces that seem to have the uncanny ability to indiscriminately cause death without human intervention. Even more baffling, these situations may have bizarre, hyper-specific conditions under which these deaths occur…

Impossible-crime-oriented BBC drama Jonathan Creek has an episode episode titled “Mother Redcap” involving an inn where bizarre deaths seem to constantly occur within the same room, at the same time… Max Afford’s “The Vanishing Trick” involves a “kinda haunted” room that constantly swallows up servants and sends them to God-knows-where…

6.) Invisible Murderer

A murder who is mysterious able to pass under your nose without detection, strangle a woman in plain view of a crowd of hundreds without being seen, and murder in rooms guarded on all sides. This impossible problem involves the situation of a murderer who is able to defy detection even when the situation dictates that they would be seen.

Such an impossible crime makes up the principle murder of Christianna Brand’s Death of Jezebel, in which a murder is committed in front of a crowd of hundreds of spectators to a medieval pageant at top of a tower, the only viable entrance to which was also in view of the audience. Derek Smith’s Whistle up the Devil features a murder in a jail cell whose sole door was observed by the narrator and a reliable witness at all times the murderer must’ve walked through the door, and yet neither of them saw any such killer…

7.) Vanishing

Whether person or object, the problem of an impossible vanishing involves something disappear when there’s no reasonable way for this to occur. While it can often overlap with locked-room mysteries, footprint mysteries, or invisible criminals, this class of impossible crime also accounts for people vanishing in front of witnesses like a magician, or thefts of objects while in another character’s hands…

Roger Ormerod’s More Dead than Alive features a world-renowned magician who seems to disappear impossibly from his locked-and-sealed laboratory. Edward D. Hoch wrote multiple stories featuring a Great Thief-cum-Detective Nick Velvet, including the impossible caper “The Theft of the White Queen’s Menu” in which three impossible thefts occur: the theft of a roomful of furniture in a matter of just a few minutes, the theft of a roulette wheel from a crowded casino and yet nobody saw it leave, and the theft of rival thief The White Queen’s menu while it is held in her hands! Quite spectacularly, Paul Halter’s story “The Celestial Thief” involves the disappearance of all of the stars in the night sky as an astronomer is watching them from his telescope!

8.) Materialization

Diametrically opposite the previous category, impossible materializations involve the production of an object or person where it very well could never have been! A man manifesting within a sealed room, a plane appearing in the sky when it had nowhere from which it could’ve come, and poison appearing within a test-tasted dish…

James Yaffe’s “The Case of the Emperor’s Mushrooms” involves the murder of Emperor Claudius of Rome, who dies to a plate of poisoned mushrooms — quite mysteriously however, the royal food-tester had eaten a portion of the food without dying, and so the poison must have appeared while in the emperor’s hands…

9.) Prophecy, Clairvoyance, and Predictions

The fortune-teller tells you that you will die on June 4th, 2022 at 5:25 PM… and, lo and behold, you find yourself dead at the appointed time! People coming into possession of knowledge which they should never have been able to learn makes up this class of impossible problem.

There are, in fact, two real-world examples. “The Greenbrier Ghost” of West Virginia is a story about a woman who divines knowledge of the cause of her daughter’s death when the young women’s death was named natural. “The Horse Room” involves a group of women named the Blondie Gang who were robbing casinos blind in the 1940s, and the way they managed to cheat at horse-race betting in a room where no information could travel in or out… John Dickson Carr’s The Reader is Warned also involves a psychic predicting a murder, down to the very minute it’ll occur.

10.) Ghost, Witches, and Miscellaneous Supernatural Jiggerypokery

This, ultimately, is a “miscellaneous” category for all impossible crimes that appear to be ghosts, magic, or the supernatural at work but don’t fit into the other categories for being too specific. The appearance of a floating ghost in a room, a woman casting a spell that appears to come true, or the commission of a seance all fall into this category.

John Sladek’s Black Aura has a man suspended in mid-air and walking without any support in front of witnesses, and Hake Talbot’s Rim of the Pit features floating men, ghosts, seances, and nearly every supernatural occurrence you could hope to dream of. “Miracle on Christmas Eve” by Szu-Yen Lin involves the impossible delivery of gifts by a man who could only be Santa Claus himself… Also, suffice it to say, Scooby-Doo anyone?

11.) Impossible Technology

Mind-reading devices, hover-boards, and teleportation machines don’t exist… or do they? The impossible technology problem involves story where a piece of technology is presented as entirely genuine, but there is no scientific way for such a machine to exist. How could this bizarre feat be faked and manufactured?

In The Great Ace Attorney 2: Resolve of Ryuunosuke Naruhodou‘s third case, Twisted Karma and his Last Bow, defense attorney Ryuunosuke Naruhodou is commissioned to defend a scientist of murder. This scientist constructed a teleportation machine that’s capable of de-materializing a man in one place, and rematerializing him in another spontaneously. He was demonstrating the machine at a science exhibition when the device malfunctioned, causing the man to appear above a glass tower, suspended freely in the middle of the air! The man would then crash through the roof of the tower where it would be impossible to approach him… and yet, when the police arrive, the man was stabbed to death. Because of the location of the body, it’s only possible for your defendant to have stabbed the man before his teleportation! And so, in order to prove his innocence, you also have to prove how the entirely impossible feat of teleportation could’ve been faked in front of a massive audience…

12.) The Inverted Howdunit

One of two Impossible Alibi problems I described, this Doylist impossibility tiptoes the line between the inverted mystery (mysteries in which we know of the killer and their plot ahead of time) and the impossible crime. In the Inverted Howdunit, we are privy to the identity of the killer very early — however, unlike most such stories, in the Inverted Howdunit we only know the killer’s identity, but we do not know how they committed the crime… or how they managed to construct an airtight alibi! This impossibility hinges on knowing the identity of the killer, but it appearing nonetheless impossible for them to be guilty.

Roger Ormerod’s Time to Kill features a murder by an ex-convict — however, the ex-convict never once left the narrator’s sight during the period during which the murder must’ve taken place! In Detective Conan Volume 2, the case “Mysterious Shadow Murder Case” involves a man who committed murder while unmistakably in another country at the time… Agatha Christie’s “A Christmas Tragedy” has Miss Jane Marple describe a murder she once solved in which she knew the killer’s identity… and yet the killer had an impenetrable alibi!

13.) Suspect X

Nine people are trapped together on an island. One person wanders off, leaving the remaining eight people together in the dining room. The ninth person is soon heard screaming, and when the eight people arrive…. they find him dead! And yet, this is impossible… he hadn’t committed suicide, everybody was watching each other at all times..! Is it possible that an Xth suspect was on the island, killing them from the shadows?

Suspect X is the second “impossible alibi” problem I described in my post on the topic. This impossibility essentially dictates that, in a closed-circle mystery, the crime is only possible if you assume the presence of one extra person whose existence in the closed-circle is itself also impossible. The solution could involve explaining the presence of this extra person, or ways for the killer, who is among the original cast, to commit murder despite being under constant surveillance.

Such problems appear in Agatha Christie’s And Then There Were None, in which the entirety of the cast is dead, and all apparently murdered, while isolated together on an island; NisioisiN’s Zaregoto – The Kubikiri Cycle, in which the narrator’s friend’s computer is destroyed while every living member of the cast is together in the dining room; Derek Smith’s Come to Paddington Fair, in which the victim is shot by a bullet from a prop gun which was at one moment loaded with blanks but later loaded with live ammunition, even though every member of the cast is incapable (by alibi and testimony) of tampering with the gun.

14.) Biological Impossibilities and Illogical Causes of Death

Biological impossibilities are any mysteries in which the victim faces a death which utterly defies human physiology and logic. Initially, I was going to have a separate category for “impossible falls”, those stories in which the victim falls to their death despite the lack of an elevated surface within any reasonable distance, but I decided to consolidate those two categories hear under the blanket of “Illogical Death” since I felt like they were conceptually similar enough.

Robert Randisi’s (awful) “The Hook” involves the serial killings of women who have had all their organs removed quite impossibly, despite the presence of only a very small incision through which removing the organs so cleanly would be impossible. Both Paul Halter’s “Jacob’s Ladder” and Mack Reynolds’s The Case of the Little Green Men involve a man falling to his death despite there being no elevated surfaces nearby. John Dickson Carr’s Gur Erq Jvqbj Zheqref and the first case of The Great Ace Attorney both involve a death by curare when ingested — curare can only cause death when it enters the bloodstream, and is harmless when imbibed. Paul Halter also wrote “The Robber’s Grave” in which a patch of grass is unusually unable to grow no matter what… Soji Shimada’s “The Executive Who Lost His Mind” involves someone who was murdered only minutes ago, but their corpse suggests that they’ve been dead for years…

15.) The Lonely Boat

A boat floats in the middle of a lake with a lone fisherman in it. The fisherman suddenly keels over and dies, and when the boat is recovered he’s found stabbed to death! Such a death is impossible — it would’ve been impossible for anyone to approach the boat without attracting attention or getting wet, so how much a man wind up murdered while isolated in the middle of a body of water?

I was initially unsure about whether or not to include this one, as most variations on this problem strongly overlap with the “invisible murderer”. However, I believe this problem meets all three of my criteria in theoretically creating a significant distinction in how the crime is presented and resolved…

Such a problem occurs in Joseph Commings’s “The Spectre of the Lake”, in which two men are shot from close-range in the middle of a lake, and both of John Dickson Carr’s “The Wrong Problem” and W. Shepard Pleasants’s The Stingaree Murders, in which a man is stabbed in an isolated boat.

Detective Conan Volume 2 (1994) by Gosho Aoyama

Like I promised on my review of Volume 1, much less preamble will be necessary going forward, and these reviews will be shorter, and easier to write as well as to read. I will be reminding you every post to go read my review of Volume 1, however, as that does set the scene for everything else.

Despite sitting in that early-series slump that turns so many people off of Detective Conan, Volume 2 opens with the fairly decent Casebook 4 – Mysterious Shadow Case (Chapters 1-3). The Mysterious Shadow Case opens with Richard Moore, suddenly a respected detective thanks to the intervention of Conan, has been paid an exorbitant amount of money to trail a man for three days. However, the very day afterwards, Richard’s mark has been found dead at a fire festival..! The police are 100% convinced of the guilt of the victim’s old friend… only, at the time of the murder, the friend was provably in another country! Conan, also convinced of this man’s guilt, gets to proving the trick of how he faked his alibi.

Despite often being labelled as such, this isn’t quite an “inverted mystery”. We’re loosely guaranteed the identity of the killer, but we’re not privy to his murder plot, and because the killer has an airtight alibi making this murder impossible I’ll be sorting this into that “Doylist Impossibility” category of impossible alibis. No, TomCat, I won’t be taking any questions. And yes, just to be clear, this means I consider this story the manga’s first impossible crime, and not Idol Locked-Room Murder Case (Volume 1), which I didn’t think was truly impossible.

I actually liked this one. No, it isn’t a “lost classic” of Detectie Conan lore, but it’s a minor peak in the quality you’ll be getting out of the pure detective stories of early Conan for quite a while. Like the previous two stories I discussed in Volume 1, this one turns on pretty obvious and basic clues, but the entirety of the solution wasn’t too derivative. It’s a decently clever alibi trick that kind of calls to mind a less unique and simpler version of the solution to one of my favorite Roger Ormerod novels… Don’t take this praise too seriously though, this story is not exceptional. It’ll be sitting at the “number 1” slot for a hot minute, but I won’t let it get too comfortable…

This story pivots into Casebook 5 – The Billion Yen Case (Chapters 4-7), in which Richard is asked to locate a young woman’s missing father, her “only family”. Another PI elsewhere is asked by an adult man to locate the exact same person, who also claims that he is his father, and his “only family”. The conflicting stories come to a head when the man is reunited with his daughter, only to immediately wind up murdered.

This one’s boring. Not very clever or unique, you’ll see where it’s going from begin to end. Possibly the most uninteresting way to develop this premise. Introduces under-used Conan tech in the form of the tracker badge, though. Meh…

Casebook 6 – The Haunted Mansion Case (Chapters 8-10) is a bit of a departure for the series, having Conan and three of his classmates investigating a supposedly haunted house that was once the site of a grizzly murder! The kids slowly disappear one by one under mysterious circumstances…

This one’s kinda fun, but it has some wild tonal whiplash, going from Scooby-Doo to Edgar Allan Poe in no-time flat. It’s the first appearance of the “Junior Detective League”, but other than that it’s not notable for much. Up until the end, it reads like a middle-of-the-lane Nancy Drew/Hardy Boys-style juvenile detective stories like most of the Junior Detective League stories I can think of… There is, technically, a “murder mystery” that’s solved, but it’s minor stuff, and is more there for atmosphere than anything.


Another mediocre review of a pretty middling volume. I’ll be urging you along for a while, because we’re both working through the slog together, you and me. I want to make it clear that if you see any praise I levy towards these stories that seems colored or reserved, assume there’s an implied “for this point in the series”. There’s nothing great here, but we’re getting to some really good ones… Not, you know, in the next volume, but we’re getting there.

The individual positions of these stories relative to each other doesn’t matter at this point, they’re all kinda the similar level of meh.

  1. Strange Shadow (CB#4 V2 C1-3)
  2. Haunted Mansion Case (CB#6 V2, C8-10)
  3. Idol Locked-Room (CB#3 V1 C6-9)
  4. Roller Coaster (CB#1 V1 C1)
  5. President’s Daughter (CB#2 V1, C2-5)
  6. Billion Yen (CB#5 V2 C4-7)

On A Defense of the Impossible Alibi Problem and “Doylist” Impossibilities

There’s been no end to the ingenuity of the impossible crime genre. When you see murders committed inside of perfectly sealed rooms, and stabbings in virgin snow where the killers leave no footprints, you’re only taking the daintiest of baby-steps down the iceberg of magic murders. Take a few steps further and you’ll find yourself barreling into the realms of animated murderous snowmen, disappearing hotel rooms, witchery, teleportation, telekinesis, premonitory dreams, apparitions, flying men, transmogrification, impossible golf shots, men dying from falls when there’s no elevated surfaces for miles, time travel, people running through solid brick walls, and even the apparently magical disintegration of a man in front of witnesses. All of which, mind you, must be explained through perfectly human means without reliance on far-fetched science-fiction technology or preternatural agency — or, if sci-fi tech and ghostly happenings are commonplace in your world, their rules must still be adhered (and are usually exploited to establish the impossibility…). A whole world of man-made miraculous murders that would have the skeptics of our world taken aback! When you imagine the impossible crime problem, you imagine a scenario which absolutely cannot be taken at face value, and which the characters in the story have to battle with the reality of, whether it’s through disproving the supernatural or an ostensible suicide. There’s an impossible crime tale for damn near every insane scenario under the sun a person could think of. However, there’s one situation which is so sedate in its presentation, and which, in our world, wouldn’t make anyone bat an eye, that has been something of a point of contention in the impossible crime world: the impossible alibi problem.

The “impossible alibi” puzzle comes is essentially this: we know that the killer has to be this specific person (or someone among a closed circle of suspects with proximity to the crime), usually by insistence of the book or narrator, but this specific person (or every person in aforementioned closed circle of suspects) has an apparently unassailable alibi. Usually, this alibi is vouched for and reaffirmed in some way by the narration — when the guilty party is definitely one specific person, the book also usually goes an extra step to assure the reader they aren’t being hoodwinked and that the crux of the puzzle turns decidedly on this person’s guilt. Consider if you will Columbo, where they always open an episode by revealing the killer and how they carried out the crime, and the puzzle is in figuring out how Columbo solves the mystery — the “howcatchem”. By then removing the actual knowledge of how the killer committed the crime from the formula and giving them an airtight alibi, the “impossible alibi” problem can straddle the howcatchem with the locked room mystery with ease.

What I would say makes it hard to see this problem as “an impossible crime”, per se, is that if the crime were to occur in our world we would simply not pursue it as such — and, save perhaps for the detective, nobody in the book is approaching it from that angle either. Someone who isn’t the suspect could have just as, if not even more easily, committed the crime and the “impossible” problem melts away. The problem is possible… but only so long as you take it as the events of the novel being experienced from the perspective of someone impartially involved with the affair, that is. The murder is only “impossible” to us as readers, and nobody else, and only as long as we wholesale accept a certain premise.

This is far from a fair criticism to levy against the “impossible alibi” plot. Consider if you will what I like to call “The Judas Window Problem”: a murder is committed in a locked and sealed room, only of course, inside of the room isn’t just the victim’s body, but also a living individual presumed to commit the crime; it is only when we accept that this person is innocent that the crime takes on its “impossible bend”. In many cases, there does end up being some physical evidence at least lightly suggesting that the person in the room is innocent, but there are also more than a few cases where there isn’t and the detective investigates more out of personal interest. Does it stop being an “impossible crime” story simply because you’re missing hard, physical proof the suspect is innocent? Does it become “a totally possible crime which only incidentally features a sealed room and the exact kind of trick that would be used to commit a locked-room murder elsewise” simply because the book expects us to accept some premise that wouldn’t necessarily be accepted within the confines of the story? If it feels like we’re suddenly splitting hairs here, why is it suddenly a different story when we’re expected to accept one person’s innocence, when the alibi problem is only the dichotomous opposite of accepting one person’s guilt?

Four years ago, on The Reader is Warned’s post on this very topic, Dan suggests that the “impossible alibi” problem doesn’t deserve to be called an “impossibility” because alibis don’t hold water under scrutiny and are “meant to be broken down” — and, specifically, because the suspects say “I wasn’t there”. There are two points here, “the alibi is meant to be broken” and “alibis are flimsy because they’re based on testimony”, which will be dealt with reversely.

The second point is markedly unfair; there is no novel out there claiming to feature an “impossible alibi” problem where the problem begins and ends with all of the principle suspects saying “I wasn’t at the crime scene, I was in my room!”. A crime where someone is murdered in an immediately accessible location, but everyone promises they were somewhere else with next to no corroborating information would never pass snuff as an “impossible alibi” problem. It’s when other people’s testimony and physical evidence starts to make it appear as if every alibi is assuredly true when the impossibility starts to take form.

Consider Roger Ormerod’s Time to Kill, wherein the detective all but assures us that an ex-convict he’s playing pool with is the culprit of a murder on another floor of the hotel in which they’re playing, which was proven by autopsy to have occurred during the ongoing pool game. Or, the locked-room mystery and impossible-crime story by popular Japanese author NiSiOiSiN, Zaregoto: The Kubikiri Cycle, where one of the crimes is the destruction of the narrator’s friend’s computer while every member of our classically-styled stranded island closed-circle cast testifies that every other person was in the same room at the same time at the critical moment, which is known to be the period of time when everyone was assembled together. Consider Agatha Christie’s “The Christmas Tragedy”, where we’re 100% guaranteed to the identity of the culprit but reliable testimony places him elsewhere at the time of death.

Now, of course, you could argue a lot of things that end up explaining the problem away, even though you seem to have physical evidence and other testimony supporting the alibis. Seemingly reliable testimony was actually fudged to provide the culprit with an alibi; perhaps, somehow, the time of death was obfuscated; perhaps the killer used some bizarre, unknown trick to make it look like he’s in one place when really he isn’t; perhaps the killer wore a disguise; perhaps a once-thought-dead individual in a closed-circle is actually alive, having faked their death; perhaps the crime was committed remotely through some unknown means.

…Which brings us to the first of the earlier two points. Yes, these are all possible explanations to the “impossible alibi” problem… but they’re also all possible solutions to any other number of impossible crimes! Any trick you use to commit a murder under these conditions will, like it or not, play under the same rules, with the same train of thought as the resolutions to any impossible crime, whether it’s a locked-room mystery, guarded rooms, or an invisible killer. I’d go so far as to suggest that a guarded-room mystery is fundamentally exactly the same as some styles of the impossible alibi problem in terms of how the impossibility is established and how it can be resolved. The possibility of faking alibis doesn’t preclude these sorts of problem from impossibility status, because the very heart of impossible crimes is “an entirely possible series of events fraudulently established as apparently ‘impossible'”. All impossible crimes are built on the conceit of the situation being faked in some way; there’s no reason to discriminate against the airtight alibi on these grounds, when there’s sufficient supporting information making every alibi apparently airtight and credible. Is the killer never committing murder despite being in front of the detective’s face at the key moment not impossible enough?

The “impossible alibi” differs in no way from any other impossible problem.

Does it require the onus of special care in setting up the alibis to truly and properly make them appear reliable and airtight? Yes, but in very much the same way guarded rooms demand the onus of special care in establishing the faithfulness of the guards, the way that the Judas Window problem demands special care in establishing the innocence of the person locked inside of the room, or the same way that locked-room murders demand special care in establishing when, where and how the door was locked, the same way that snowprint murders demand special care in establishing when the footprints were created and when the snow stopped…

Can the information that establishes the alibis as credible be forged? Yes. The same way the details the establishes the lockedness of a locked-room, or the nature of a snowprints mystery can be faked and forged. Faking the details and making them appear reliable is quite literally the heart of misdirection and deception. All details can be faked, forged, and tricked, not much more more difficultly than an alibi could be — and all deceptions which are considered true and proper solutions to each and every single one!

Does it demand extra conditions to function as an impossibility for the reader? Yes; in fact, it’s the perfect polar opposite to the Judas Window problem. One demands you accept the guilt of a person known to be inside of the room; the other demands you accept the innocence of a person known to never be at the crime scene.

At this point, I propose establishing categories of impossible crimes dubbed “Doylist” and “Watsonian”. A “Watsonian” impossible crime is an impossible crime for the benefit of the characters in the story. Your locked-room murders, your snowprint murders. Murders which, should they occur in our own world, would demand acceptance of no conditions beyond the existence of the crime itself to be considered “impossible”. The “Doylist” impossible crime is an impossible crime for the benefit of the readers. Murders which demand acceptance of some additional premise which nobody in the story is obligated to accept but which we, as readers, must note when considering the problem. Naturally, the impossible alibi falls under this category, but it is not alone; the “Judas Window Problem” falls under this category. I’d also argue defensible coincidences, like “rooms inciting heart attacks”, more than fit here, for demanding the reader accept the condition that there is foul play, and that it involves the “killer” room. Guarded rooms also demand to some degree our acceptance that the “guards” are reliable and faithful for the impossibility to function, and many versions of the “invisible killer” problem demand our good faith that the crimes aren’t suicides or that witnesses aren’t lying.

The “impossible alibi” is more than deserving of being considered an impossible crime problem, true and proper, even if it does demand the special “Doylist” distinction — something which it wouldn’t even be the first to do. Any mystery where the problem relies on the assurance that the killer is one specific individual, or one among a static group… and where sufficient evidence is provided to allow that the killer could never have even approached the crime scene… is as worthy of its impossible status as any other. In solidarity with the “impossible alibi” problem, I will use it as a category for “impossible crimes” in this blog from this point going further, as long as I feel comfortable asserting that the novel does in fact create an impossible situation from the alibi problem, or as long as someone doesn’t convince me that I’m wrong.

So, what do you say? Do you believe that the “impossible alibi” problem is a fair classification of impossible crime, or should it stay firmly out of the realm of the impossible for good…?