Reverse Whodunnit

"Chief Wiggum: Hey, I crack cases all the time. Like the case of the symphony conductor who murdered his star cellist.

Lou: That was an episode of Columbo, chief. They show you who the bad guy is at the beginning of each one.

Wiggum: Yeah, but you have to remember!"

- The Simpsons

Also known as the "Open Mystery"; a style of Crime and Punishment Series show popularized by Columbo.

The traditional mystery challenges the viewer to solve the mystery along with the detective. Usually, the viewer is disadvantaged by the fact that the detective knows more than the viewer (We Would Have Told You But; Tomato Surprise). But in the Reverse Whodunnit, the advantage goes to the viewer: we actually get to see the murder as it is committed.

The "mystery" for the viewer is not "whodunnit" but "howtcatchum." We know who, what, where, when, and why, perhaps in more detail than the detective will ever know. For the viewer, the question is: how will the detective solve what appears to be a perfect crime?

A successful Reverse Whodunnit requires a very intelligent criminal, capable of designing a crime complex enough that its solution remains interesting even if you already know who did it and why.

It also requires a far cleverer detective than you can get away with in a standard Whodunnit, because the writers can not rely so much on misdirection to make his job look hard. For example, solving any Scooby Doo mystery would be trivial if Velma let the audience get a good look at the clues instead of hiding them until The Summation.

Sometimes called a "Police Procedural" (but not to be confused with the Police Procedural) because its focus is on the procedure rather than the solution.

This was probably invented by R. Austin Freeman in 1912, in his collection of detective short stories The Singing Bone, which featured Dr. Thorndyke. He called this concept the 'inverted detective story'.

A subtrope of Internal Reveal.

Anime & Manga

 * In Death Note, the main character is secretly an infamous murderer and the series follows his attempts to avoid suspicion from police and a few genius detectives.
 * The long running anime Detective Conan does these occasionally to mix things up. In these cases, there's only one likely suspect from Conan's point of view, and he has to figure out how they set up a false alibi.
 * Monster. In this instance, the hero himself knows who the killer is for almost the entire series, it's just finding and capturing him that's the problem.
 * In the Ace Attorney manga's first case, the killer is shown in silhouette in the prologue section after the murder.
 * MW has Meguro having guessed right that Michio Yuki is the Serial Kidnapper.

Film

 * Diabolique. Alfred Fichet is the inspiration for Columbo, too.
 * The Alfred Hitchcock film Dial M for Murder.
 * Fracture: "I killed my wife...Prove it."
 * Memento plays the hell out of this trope. We see who  was the murderer and so does Lenny in the very first scene. However, the film goes in reverse, and then with him only remembering scenes in several minute intervals, as we see the outcome and learn the clues as he does while already being "spoiled" to the ending, because of it going in reverse. For the first half, the viewer is able to string together the various short bits of color and he is not, involving quite a bit of mental work, but we still know more than he does because we can remember it.
 * Frequency has shades of this. Although, its less a howcatchem than a howproveit. The main characters find out who the killer is fairly early on...the problem is, they only find this out by collaborating over a 30 year time gap (they can communicate via HAM radio). So, they somehow have to prove who the killer is to the cops, with evidence the cops will actually believe.

Literature

 * Dr. Thorndyke was one of the first to do this; several of his stories will show the killer performing an apparently perfect coverup in the first half, then following it with scientific deduction through the second half.
 * These were followed by Malice Aforethought (1931) by Anthony Berkeley Cox, and most of the Department of Dead Ends stories by Roy Vickers.
 * The subtitle of Feet of Clay is "A Discworld Howdunnit", though the actual story is a classic whodunit.
 * Although figuring out how  is crucial to solving the who.
 * Unless you're just really good at
 * Examples from literature, later adapted into films: The Day of the Jackal by Frederick Forsyth and A Kiss Before Dying by Ira Levin.
 * Although in The Day of the Jackal the investigators locate the assassin by pusuing a line of investigation based on.
 * Captain Leopold Incognito had the variation that the villain (and reader) knew Leopold would be making an undercover investigation, but did not what identity he would be using.
 * Used to great effect by Mary Higgins Clark in numerous mystery novels.
 * The final book of Larry Niven and Steven Barnes's Dream Park trilogy, The California Voodoo Game. The first two books were Whodunits; in this one, almost at the start, we see the villain kill someone to help cover up a theft, but we're not told what the theft is. So not only do we read to see how the heroes figure him out and catch him, but to discover what was stolen. Has two brilliant The Plans colliding one from each side.
 * The Demolished Man by Alfred Bester spends its first five chapters showing a man commit an incredibly complex murder, then the rest of the book follows the officer who suspects he did it and is trying to prove it. Subverted a bit because
 * The Isaac Asimov short story The Singing Bells opens with the murder, and then introduces the detective and proceeds to the investigation.
 * Almost everything written by Jeffery Deaver is this - the novels often containing passages told from the point of view of the villain early in the novel, and spend the rest of the story charting the battle of wits between the good guys and the bad.

Live Action TV

 * Columbo is a pioneer for the "howcatchum" style, and the creators invented the term. Rather than puzzle out the perpetrator from a variety of suspects, Columbo always focuses his investigations on the actual perpetrator and uses his unassuming style to amass enough evidence for an arrest.
 * Mrs. Columbo follows a similar format.
 * Monk shifted toward this after its first season.
 * Although Monk's recaps still filled in a lot of gaps and would give the audience the context and usually more details of the murder itself.
 * Diagnosis Murder does this a great deal.
 * Law and Order Criminal Intent used this format in its first couple of seasons, showing the whole crime at the beginning and (usually) setting Goren and Eames on the culprit and harrying them into showing their hand. Later seasons show the circumstances around the murder, but leave the killer's identity ambiguous.
 * Otherwise on Law & Order, if at first the cold open looks to be setting up a Reverse Whodunnit, with a crime appearing imminent, you can expect that they'll subvert it once the near-victim trips over someone else's dead body, which will be the actual focus of the episode's investigation.
 * Variation in Frasier. One episode starts with an entirely innocent explanation for why a cracked skull would end up under the floorboards of Frasier and Niles' old house, the remainder of the episode consists of the two of them discovering it and totally misinterpreting the evidence.
 * The short-lived Police Squad! series by Zucker, Abrahams, and Zucker.
 * The CSI episode "Killer" alternates its point of view between the killer and the CSIs, showing his motivations and attempts to cover up his crime as the investigators get closer.
 * The second season of Dexter is about searching for the Bay-harbor butcher, who happens to be Dexter Morgan. However, it's less about "How do they catch him" then "How does he fool them".
 * Also shows up in the third and fourth seasons of Dexter.
 * The Wire. Deangelo: "Tap, tap, tap." Mcnulty and Bunk: "Fuck."
 * The Perry Mason episode "The Case of the Lucky Loser" used this: at the very beginning, we see a man follow his cheating wife, then shoot her lover. The man's nephew is accused of the crime, and the family hires Perry to clear the nephew without implicating the uncle.
 * Many episodes of Criminal Minds.
 * Furuhata Ninzaburou is Columbo in all but name; just before the last act, the titular detective "pauses" the action to address the audience to give them hints as to why he believes that the chief suspect did it, and what evidence there is to force a confession.
 * Every episode of Luther reveals the villain early on, with the drama coming from how Luther will catch the suspect.
 * White Collar has shades of this. The protagonists usually figure out who the bad guy is pretty quickly, and the rest of the episode is spent on how they catch him.

Video Games

 * The first two cases in Phoenix Wright Ace Attorney are Reverse Whodunnits, likely to ensure that you are on your client's side right from the start. In the first case, Frank Sahwit is the only witness called to the stand besides the defendant.
 * Very often the nature of the actual guilty party is blindingly obvious as soon as you meet them (at least to anyone sufficiently Genre Savvy or paranoid), so an element of this exists in most of the cases throughout the series. The real fun is in figuring out how to PROVE it.
 * A lot of the cases actually throw U-Turns at you. For example, some people who look extremely evil are completely innocent and vis-versa, almost too the point where the true killer becomes obvious because you KNOW they will trick you, so you look for the least likely person.
 * The first case of Ace Attorney Investigations Miles Edgeworth also starts like this.

Real Life

 * Former Attorney General Robert Kennedy once formed a task force known as the "Get Hoffa Squad" whose sole purpose was to find incriminating evidence on Teamster leader Jimmy Hoffa. Three years later, they secured a conviction.
 * This is very common in corruption or organized crime cases, where the problem is not knowing who the bad guy is, but building a case against him.