How To Plan a Crime When Writing a Mystery Novel

A crime is an illegal activity. A crime is something someone commits that is an offense to the law. A crime is a robbery, a murder, assault, kidnapping, etc.

It’s not good.

So. How does one commit a crime?

I’ll tell you how, but only the skeleton of it. The rest you’re going to have to figure out on your own. You can’t expect me to do all the work, can you? No, of course not.

Step One.

Plan the crime before you do anything else.

Step Two.

Now — Wait, what? What do you mean you don’t know how to plan the crime? What are you even doing with your life if you can’t even figure this part out on your own?

Alright, come on…

How To Plan a Crime when writing a mystery novel Rachel Poli

Let’s start back at the basics, shall we?

A mystery is a puzzle, a riddle. Maybe a secret or a problem. A mystery is something of the unknown. The only way to solve said riddle, puzzle, problem, whatever is to ask yourself basic questions.

Who, What, Where, When, Why, and How.

Yes, I’m bringing you straight back to elementary school. The only difference is that we’re not trying to write an essay from analyzing a book. No, we’re going much darker than that. We’re adults now.


“Who” refers to people, the characters of the story. Each character has to have something to do with the crime whether they like it or not. Are they a witness? A victim? An investigator? A suspect? Maybe they’re just there to throw the investigator off the trail and take the reader along with them.

Once your have your characters lined up in a row, give them each a job.

  • Who are the victims?
  • Who are the culprits?
  • Who are the witnesses?
  • Who are the suspects?
  • Who are the accomplices?
  • Who are the investigators?
  • Who discovered the crime(s)?


The “what” may not be known right off the bat, but depending on the situation some answers may be more obvious than you think.

  • What is the problem/crime/secret? (What happened?)
  • What was the weapon/what was stolen?
  • What was the motive?


“Where” is how you set the scene for yourself, your characters, and your readers. It’s a little tough to investigate when you can’t see the scene surrounding you.

  • Where does the overall story take place?
  • Where does the crime take place?
  • Where was the victim(s) when the crime took place? (Unless it’s a murder, the victim doesn’t necessarily have to be around.)
  • Where was the weapon(s)/stolen item or person?
  • Where was the culprit(s) hiding?
  • Where were the witnesses when the crime occurred?


Time matters.

  • When did the crime take place?
  • When was the crime discovered?
  • When were the authorities called/brought to the scene?
  • When does the investigator find his first, second, third clues, etc.?
  • When does the investigator solve the crime?
  • When does the culprit(s) get caught/confess?


The reason is key. You need to be able to explain to your readers why this mystery happened in the first place, why it was a good story to tell.

  • Why did the culprit commit the crime?
  • Why did the culprit choose that particular victim?
  • Why was your investigator the best one to solve the case?
  • Why did the crime take so long to solve? (Why did it take not long at all to solve?)


I assume you’re writing a fictional mystery. In which case, your readers still need to know the “how.” Everything needs to fit together nicely like a puzzle and be explained as realistically as can be.

  • How long was the overall investigation?
  • How did the culprit pull off their crime?
  • How was the culprit caught?
  • How did the investigator figure it out? (How did they finally piece it all together?)

Some of these questions are redundant, but I think it’s good to repeat yourself sometimes. It helps you remember and helps you catch mistake or plot holes.

Some questions you may not need. I’m sure there are other questions out there that you can ask yourself that are not on this list.

This is how I plan my mystery novels. I plan the crime before any actual writing begins so I, as the writer, am the investigator.

Now all you need to know is how to implement this crime.

This post was revived from Mystery Month’s 2015 post: Who Dun It? 

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29 thoughts on “How To Plan a Crime When Writing a Mystery Novel

  1. Thanks Rachel, I just found #ACrimeChat twitter hour, where you can ask any crime related question to help your writing. Every Wednesday at various times across the time zones. Readers can follow @SueColetta1 for more info.

  2. A very informative post, Rachel. Thanks a lot for sharing it. šŸ™‚
    I’m currently serializing a murder mystery on my blog every Friday that I’d written around three years ago (I never finished it). Now that I’m reading this post, I feel like giving it a second chance (except that I feel there’s nothing new about the plot). I don’t know if you’ve read it. It’s called ‘Cold Scent’. If you do have some time on your hands, I’d love to have your opinion on it.

    • Thank you! I’m glad you enjoyed the post.
      And thanks for the follow. I hope you like the rest of the blog. šŸ™‚

  3. Rachel, this post couldn’t have been better timed for me. After I finish my current novel, I have a crime mystery I have just started to plot. Your information is incredibly helpful. Well done!

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