How to Write Crime Fiction: The Complete Guide

Crime fiction is the genre that uses a crime to X-ray a society: it doesn't only want to know who killed, but what that murder says about the world that allowed it. To write it you need a believable case, an investigator with wounds of their own, clues that play fair with the reader, and a police procedure that actually resembles the one in your country.

There's an exact moment when a Spanish crime novel loses its reader, and it's almost always the same one: when the inspector flashes a badge, says "you have the right to remain silent" and calls forensics so the lab can hand over the DNA that same afternoon. That isn't crime fiction: that's CSI dubbed into Spanish, and the reader smells it within two pages. In this guide you'll see what really defines the genre, how to build clues so they play fair and — this is the part almost nobody covers — how a homicide investigation actually works in Spain, with the law in front of us. If you're starting from scratch, begin with our general guide on how to write a novel and come back here for the genre-specific part.

What crime fiction is (and how it differs from detective fiction, thriller and mystery)

Crime fiction — novela negra in Spanish, noir fiction in English — is the novel of the professional world of crime, where the line between good guys and bad guys blurs and solving the mystery is not the main goal. It was born in the United States in the 1920s, in the pulp magazine Black Mask, founded in 1920 by H. L. Mencken and George Jean Nathan. The Spanish name comes from there and, above all, from the Série Noire, the imprint that Marcel Duhamel founded at Gallimard in September 1945. It's worth separating four labels that get used as synonyms and are not:

• Detective fiction, or the puzzle mystery. The crime is a logical problem. An exceptional investigator assembles the pieces and, by solving it, restores order. This is the British Golden Age school: Christie, Sayers, Allingham, Marsh.
• Crime fiction (noir). The crime is a symptom. What is really being investigated is a sick society, and the ending rarely fixes anything. The detective goes home dirtier than they came out.
• Mystery. An umbrella label, more commercial than technical: it covers everything from the cozy to the pure puzzle. Its promise is an unanswered question the reader wants to close.
• Thriller. Here what matters is not so much what already happened as what is about to happen. Its engine is anticipated dread, not investigation. If your novel is about preventing a catastrophe with a clock ticking, you're not writing crime fiction: you're writing a thriller, and the tools are different.

In practice almost everyone mixes, and that's fine. What you can't do is not know where you're putting the focus: it determines where you place the tension, how much the reader knows and what you owe them at the end.

What defines a good crime novel?

Social criticism is the DNA of the genre, not a prestige add-on. Sweden's Maj Sjöwall and Per Wahlöö said so bluntly when they wrote the ten Martin Beck novels between 1965 and 1975: they wanted to use the crime novel as a scalpel to open up the belly of the welfare state. They conceived the series as a single novel of three hundred chapters spread across ten books, one a year. That's the level of ambition we're talking about, and from it come the three pillars of the genre:

• A crime that points at something. The body is a door. If all you find behind it is a killer with a private motive, you have a puzzle; if what appears is a town hall, a construction company and thirty years of silence, you have crime fiction.
• Moral ambiguity. Nobody is clean. The honest cop has a dirty deal in his past; the victim wasn't innocent; the culprit has reasons you almost understand.
• Procedural plausibility. The crime-fiction reader is the fussiest of all: they'll forgive a badly explained dragon, but not a judge authorising a wiretap over the phone in two minutes.

1. How criminal investigation really works in Spain

Here is the gap almost no guide covers, and it's the one that separates a credible Spanish crime novel from a CSI set in Madrid. Everything that follows has been checked against the law of Spain; if your novel takes place in another country, do exactly the same with its own rules.

Who investigates what (and why the map matters)

In Spain there is no such thing as "the police": there are several forces with different territories and powers, and the division is set by article 11.2 of Ley Orgánica 2/1986 on Security Forces and Corps. If your body turns up in a provincial capital, the case belongs to the Policía Nacional (National Police); if it turns up on a country road twenty kilometres away, it belongs to the Guardia Civil. That geographical detail decides who your protagonist is.

Two nuances that give you a lot of narrative mileage. The territorial split does not lock each force in: the Policía Nacional can investigate anywhere in the national territory, and both forces are obliged to act outside their area when ordered by a judge or by the public prosecutor (arts. 11.3 and 11.4). And if there's a conflict of jurisdiction, the force that carried out the first actions takes charge until it is resolved (art. 11.5): there's a free piece of office friction for you.

On top of that, officers in judicial police units live with a dual chain of command that does not exist in the United States: organically they report to the Ministry of the Interior, and functionally to the judge, court or prosecutor handling the case (art. 31.1 LO 2/1986 and art. 126 of the Spanish Constitution). Translated into plot: your inspector has two bosses, and they don't always want the same thing.

The juez de instrucción: the difference that changes everything

This is the structural mistake that ruins the most Spanish crime novels. In the United States the police investigate and the prosecutor (the district attorney) decides whether to charge. In Spain, no: article 303 of the Ley de Enjuiciamiento Criminal (LECrim, Spain's Criminal Procedure Act) assigns the building of the case file to investigating judges. Under Spanish law a criminal investigation is directed by a judge: it is the judge who authorises searches and wiretaps, who orders the autopsy and who decides which lines of inquiry are pursued.

That reconfigures your whole plot. Your police officer doesn't decide: they ask. Every advance goes through a judicial order, and there you have legitimate, inexhaustible tension — the judge who won't authorise, the one who authorises too late, the one who gets too involved. The secreto de sumario (secrecy of the case file) is yours to use too: the judge may declare it, either on their own initiative or at the request of the prosecutor or the parties, for no longer than one month, and must lift it at least ten days before the case file is closed (art. 302 LECrim).

Removing the body, step by step

This scene appears in almost every crime novel and is written badly in most of them. Here's how it actually works in Spain:

• The judge orders it, not the police. In the case of a violent death or one suspected of being criminal, it is the investigating judge who describes the state and circumstances of the body and directs the procedure (arts. 335 and 340 LECrim).
• A judicial commission travels to the scene: the duty judge, the forensic pathologist and the Letrado de la Administración de Justicia (court clerk, formerly the judicial secretary), who is the one who certifies what happens. The judicial police are already there, preserving the scene.
• The judge may not go. Article 778.6 LECrim allows the judge to authorise the forensic pathologist to attend in their place. This tends to happen when there are no signs of criminality at first sight: a judge who decides not to go down to the wrong place is, in itself, the opening of a novel.
• The autopsy is the rule. It is carried out by forensic pathologists even when an external examination allows the cause of death to be presumed (art. 343 LECrim). Only the judge may waive it, if the pathologist gives a full opinion on the cause and circumstances (art. 778.4).
• The body goes to the Instituto de Medicina Legal y Ciencias Forenses (Institute of Legal Medicine and Forensic Sciences). There is one in every city that hosts a High Court of Justice (art. 479 LOPJ). The more complex toxicology and DNA analyses go to the Instituto Nacional de Toxicología y Ciencias Forenses, with departments in Madrid, Barcelona and Seville and a branch in La Laguna.

What happens to a detainee: 72 hours, a piece of paper and three hours

Article 17.2 of the Spanish Constitution is categorical: preventive detention may not last longer than the time strictly necessary and, in any event, within a maximum of seventy-two hours the detainee must be released or brought before the judicial authority. That's a ceiling, not a quota to be used up. Only in terrorism cases can it be extended by up to a further 48 hours, subject to judicial authorisation (art. 520 bis), and incommunicado detention has its own limit: five days, extendable by another five in specified cases (art. 509).

And no, in Spain nobody "reads you your rights". Article 520.2 LECrim requires that the detainee be informed in writing, in plain and accessible language, in a language they understand, and be allowed to keep that written statement for the whole of the detention. Your detainee has a folded piece of paper in their pocket; they don't listen to a speech. Two more golden details:

• Legal assistance cannot be waived, except where the detention is exclusively for road-safety offences (art. 520.8). Your murder suspect cannot "waive a lawyer" in order to talk to the inspector alone.
• The lawyer has three hours. The appointed lawyer must attend as quickly as possible and always within a maximum of three hours from receiving the instruction (art. 520.5). There's your hourglass for an interrogation scene.

If the detention is unlawful, habeas corpus is available (Ley Orgánica 6/1984): the judge must rule within twenty-four hours of the order opening the proceedings, and neither a lawyer nor a court representative is needed to request it. Pre-trial detention has its own time limits: up to one year if the sentence is three years or less, up to two if it is longer, with a single extension (art. 504 LECrim).

The trial: nine jurors, no gavel

In Spain, manslaughter and murder are tried before a Tribunal del Jurado (jury court): Ley Orgánica 5/1995 includes in its closed list the offences "of homicide (articles 138 to 140)", which cover murder. The trial is held at the Audiencia Provincial (provincial court), with nine jurors and a presiding judge, plus two substitutes. Unanimity is not required: seven votes for guilt, five for anything favourable to the accused. Offences that go to the Audiencia Nacional — terrorism, for example — never go before a jury. And three courtroom details almost nobody gets right:

• Spanish judges don't use a gavel. The Spanish tradition is a small handbell; the gavel is Anglo-Saxon and, above all, it's cinema (Confilegal).
• The police report is not evidence. Article 297 LECrim says it plainly: police reports "shall be treated as complaints for legal purposes". What officers testify to at trial about facts within their own knowledge counts as witness evidence; the document on its own convicts nobody.
• There is such a thing as acusación popular. Article 125 of the Spanish Constitution and article 270 LECrim allow any Spanish citizen to bring a private prosecution even if they were not the victim of the offence. It doesn't exist in the United States, and it lets you put an association, a political party or an obsessed neighbour in the courtroom.

2. The investigator: types that work and the mistake of copying the American detective

The most common mistake made by a first-time Spanish novelist is to take Philip Marlowe, give him a flat in Lavapiés and ask him to investigate a murder. He can't. In Spain, a private detective cannot investigate offences that are prosecuted ex officio: Ley 5/2014 on Private Security expressly forbids them from entering into contracts for that purpose and requires them to report immediately to the competent authority any such matter that comes to their knowledge. Homicide is a public offence. End of story.

The law also regulates them as a profession distinct from that of security guard or private bodyguard, which are the categories that provide services with firearms. Your Spanish detective is a university-qualified private investigator handling infidelities, workplace absenteeism and missing persons. It's a magnificent character, but it isn't Marlowe: if you want them to get mixed up in a murder, write how they get in where they shouldn't. That transgression is the plot, not a detail to be ignored. These four profiles do work, and each one gives you a different novel:

• The police officer. Legitimate access to the case, hierarchy, bureaucracy and awkward superiors. If they're Guardia Civil, you gain the rural world and forced postings; if they're Policía Nacional, you get the city and the station.
• The journalist. Asks questions where the police can't reach and publishes what the police can't. Their conflict is their own: the scoop versus the victim.
• The forensic pathologist or the scientist. Sees what nobody else sees and can't arrest anyone. Their powerlessness is their engine.
• The involved amateur. Someone the crime touches personally: the most fragile in terms of plausibility and the most powerful in terms of emotion.

Whichever you choose, give them what you'd give any protagonist: a desire, a wound and a contradiction. Building the character matters just as much here as in any other genre. And take care with the interrogations: in crime fiction, believable dialogue does the work that action does elsewhere. An interrogation is a fencing scene with two people sitting down.

Nobody remembers a crime novel for the killer's name. They remember it for the investigator who, on reaching the end, understood that they were part of what they were investigating too.

3. Structure: crime, investigation, twist and resolution

Crime fiction has a recognisable architecture that you can build on top of any narrative scaffolding, whether that's three-act structure or a Save the Cat! beat sheet:

• The crime. Early. It doesn't have to be on page one, but it does have to be in the first stretch: it's the contract with the reader.
• The investigation. The body of the novel. Every scene must change something: a new clue, a broken alibi, a suspect ruled out. If a scene only repeats what we already knew, it's dead weight.
• The midpoint. The initial theory collapses: what looked like a settling of scores turns out to be something else.
• The twist. The revelation that reinterprets everything you've read. Unexpected and, in hindsight, inevitable.
• The resolution. We learn who and why. But in crime fiction justice and truth don't always coincide, and that's where your final blow lands.

Playing fair with the reader: clues and red herrings

The genre imposed rules on itself almost a century ago and they still hold. In 1928, S. S. Van Dine opened his "Twenty Rules for Writing Detective Stories" by demanding that the reader have the same opportunities as the detective and that all clues be laid out plainly; his second rule bars any trickery on the reader beyond those the criminal legitimately plays on the detective. A year later, Ronald Knox set out his decalogue for the Detection Club: the detective may not solve the case by accident or by a lucky hunch, may not be the criminal, and must reveal to the reader every clue they find. In practice this means three things:

• Sow before you reap. Everything the detective uses in the revelation must have appeared earlier, even if the reader didn't know what they were looking at.
• Red herrings are built out of truths. A cheap false lead is a lie; a good one gives a true fact that points in the wrong direction because the reader misreads it. Never lie yourself: let them lie to themselves.
• Don't hide what your narrator knows. If you narrate close to a character who knows the killer and you hide that thought from the reader for three hundred pages, you're not doling out information: you're cheating. And it shows.

4. Subgenres: where each one comes from

Knowing which tradition you're writing in tells you what your reader expects and which table you'll end up on in the bookshop.

The rise of Japanese crime fiction (and why you should be watching it)

In Google Trends relative interest for "novela negra" in Spain over the last twelve months, one query stands out among those on the rise: "novela negra japonesa" (Japanese crime fiction), up +300%. That's relative interest, not search volume, but the signal is unmistakable and the catalogues of Spanish publishers confirm it.

Honkaku (本格, "orthodox", "authentic") is the Japanese tradition of the fair-play mystery, an intellectual duel between author and reader inherited from the British Golden Age. Its founding father is Edogawa Ranpo, the pen name of Tarō Hirai, who debuted in 1923 and whose name, said quickly, sounds like "Edgar Allan Poe" — the homage is literal. After the war came Seishi Yokomizo with his detective Kosuke Kindaichi, and Seichō Matsumoto pushed the genre towards social criticism. In the 1980s came shin honkaku: Sōji Shimada with The Tokyo Zodiac Murders (1981) and Yukito Ayatsuji with The Decagon House Murders (1987) put the impossible plot and clean clues back at the centre.

Today you can read them in translation: in Spain, Quaterni publishes Ayatsuji and Yokomizo, Libros del Asteroide publishes Matsumoto, and Salamandra Noir publishes Akimitsu Takagi. Read them for one very specific reason: no other subgenre teaches you better how to build a puzzle that respects the reader. Even if you write Mediterranean noir, that discipline will save your plot.

5. The setting as a character

In crime fiction the place is not scenery: it's the cause. Chandler's Los Angeles, Sjöwall and Wahlöö's Stockholm, Camilleri's Sicily, Izzo's Marseille, Vázquez Montalbán's Barcelona. All of them explain the crime that happens in them. If your novel could move from Bilbao to Seville without anything changing, your setting isn't working yet.

Spanish crime fiction has been proving that for half a century. Manuel Vázquez Montalbán launched the Pepe Carvalho series in 1972 and won the Premio Planeta in 1979 with Southern Seas, turning the Barcelona of late Francoism and the Transition into the true subject of his novels; the tribute came from Italy, because Andrea Camilleri named his inspector Montalbano in his honour. Then came Andreu Martín and Juan Madrid; Lorenzo Silva, whose duo Bevilacqua and Chamorro are Guardia Civil — and it shows in the procedural rigour — starting with El lejano país de los estanques (1998); Alicia Giménez Bartlett with inspector Petra Delicado from 1996; Dolores Redondo and the Baztán valley; Domingo Villar and his Vigo; or Víctor del Árbol, who served as a mosso d'esquadra between 1992 and 2012.

And the genre is alive off the page too. The Semana Negra de Gijón, created in 1987 with its first edition in 1988, held its 39th run in July 2026. BCNegra, born in 2005 out of an initiative by bookseller Paco Camarasa, has awarded the Pepe Carvalho Prize since 2006, which in 2026 went to Mick Herron. Getafe Negro, founded by Lorenzo Silva and now directed by Maica Rivera, held its 18th edition in October 2025. There are more than fifty crime-fiction festivals spread across Spain.

And the market? It's worth being honest: the FGEE report Comercio Interior del Libro en España 2024 (the Spanish book trade's annual domestic sales report) doesn't use the label "novela negra", but it does break out the category "Policíaca, de espionaje" (crime and espionage) within fiction, and the figure is emphatic: €91.81 million billed, 3.0% of the whole Spanish book market and growth of 18.2% over 2023. It's the third-highest-billing fiction subgenre, behind only contemporary and classic fiction (FGEE/Conecta).

How to write your crime novel in Scriptum

Crime fiction is, technically, the hardest kind of novel to hold in your head: every clue sown in chapter 3 has to pay off in chapter 28, every alibi has to hold, and the crime's timeline can't contradict itself by so much as ten minutes. Four months into writing, you no longer remember whether the suspect said he was at the bar at ten or at eleven, and that's where manuscripts fall apart.

That's what two pieces of Scriptum are for. The World Bible lets you file every suspect with what they know, what they're hiding, their alibi and which clues point to them, and also lets you store the procedural details you researched so you don't have to reinvent them halfway through. And the Planner lets you lay out, separately, the real timeline of the crime — the one only you know — against the timeline of the investigation, which is the one the reader sees. Seeing them side by side is the fastest way to spot the hole before a review does. Since Aura AI knows that Bible, it can warn you that the witness in chapter 12 couldn't have known what they've just said. You can see everything it includes before you decide.

Reading to master the genre

Read them with a writer's eye: notice when the body appears, how the clues are placed, how much information the narrator gives you and at what moment they decide to give it.

Common mistakes when writing crime fiction

• The Spanish CSI. Labs that return DNA in an afternoon, police officers ordering searches on their own authority, prosecutors directing the investigation. In Spain a judge investigates. Do your research or invent a country.
• The private detective who investigates murders. Spanish law expressly forbids it. If you still want to include one, write the consequences of them breaking the rule.
• Solving it by chance. Having the killer confess on their own, or the detective "get a hunch", is exactly what Knox banned in 1929. The solution comes out of the investigator's work.
• Hiding information from the reader. Doling it out is legitimate; hiding what the narrator knows is cheating. The reader must be able to solve it and simply not have done so.
• The killer who shows up on page 300. If the culprit wasn't sown, the revelation isn't a twist: it's a fraud.
• Confusing crime fiction with the thriller. If your tension comes from a future threat and not from a past crime, you're writing something else. Not worse: different, and it calls for different tools.
• A crime with no society behind it. Without social criticism, without moral ambiguity and without a place that explains what happened, you have a puzzle. It may sell, but it isn't crime fiction.

Frequently asked questions

Conclusion: the crime is the excuse

Writing crime fiction isn't about inventing an ingenious murder: it's about choosing which part of the world you want to light up and using a body as the torch. The puzzle is the engine, but the novel is what you see while the investigator walks. That's why the greats of the genre aren't remembered for their twists, but for their cities, their tired police officers and that uncomfortable feeling that, when you close the book, nothing has really been fixed.

And that's why rigour matters so much: every procedural detail you get right is a brick of credibility, and every badly copied CSI is a crack. Do your research, sow your clues, play fair and let the place speak. If you want a tool that can hold all that machinery together, that's exactly what Scriptum does.