How to Make Every Suspect Look Guilty

I find that one of the most enjoyable parts of reading a murder mystery is suspecting absolutely everyone. I like to give my readers several suspects to doubt :)

Anyone can be a suspect

The friendly neighbour? Suspicious.

The grieving best friend? Very suspicious.

The person who says, “I hardly knew her”? Practically waving a red flag.

But when you’re writing a mystery, creating suspects isn’t only about making everyone look shifty. A good suspect needs more than a dramatic glance, a missing alibi or a habit of appearing at exactly the wrong moment.

A strong suspect needs a secret.

I believe that’s what makes them interesting. In a murder mystery, not every suspect is the killer, but every suspect should be hiding something. That hidden truth gives them a reason to lie, behave strangely, avoid questions or point suspicion elsewhere.

And that’s where the fun begins.

When I think about suspects, I don’t only ask, “Could this person have committed the crime?” I also ask, “What are they afraid the detective will discover?”

That second question is often more powerful.

A suspect might be hiding an affair, a debt, a betrayal, a family argument, an old grudge or a private shame. None of these things automatically make them a murderer, but they can make them behave like someone with something to lose.

That’s useful because readers don’t just follow clues. They follow behaviour.

If someone lies about where they were, readers notice. If someone gives too much information, readers notice. If someone goes quiet when a certain name is mentioned, readers definitely notice.

Make their behaviour suspicious, but still fair.

A mystery shouldn't cheat the reader. The suspect’s actions need to make sense once the truth is revealed. If they lied, there should be a reason. If they panicked, there should be something they were trying to protect. If they looked guilty, the reader should later understand why, even if they weren’t the killer.

This is what makes red herrings work. A red herring should never feel random. It should come from a real secret, a believable motive or a genuine misunderstanding. The reader should be able to look back and think, “Ah, that’s why they acted that way.”

Another useful thing is to give each suspect a motive that feels emotionally believable. Money, revenge, jealousy, fear, protection, shame, betrayal and obsession can all work, but the motive has to connect to the victim in a meaningful way.

The victim matters because every suspect’s relationship with the victim tells the reader something. Who loved them? Who resented them? Who needed them silent? Who benefited from their death?

That’s where suspicion starts to build.

A good mystery should let suspicion move. One suspect might look guilty early on, another might become more suspicious halfway through, and someone quieter might suddenly become important near the end. If the same person looks guilty all the way through, readers may solve the case too quickly.

For me, the goal isn’t just to create suspects who seem guilty.

Create suspects readers want to question.

Because the best suspects don’t simply make us ask, “Did they do it?”

They make us ask, “What are they hiding?