MO (Modus Operandi) & Signatures | Crime Scenes & Killers

Your Modus Operandi (MO)

The MO (Modus Operandi) and signature often get mixed up. But there is a difference. And even an overlap, where a particular behaviour could be both the MO and Signature depending on the purpose it holds for the individual. And like the patterns seen in shows like Mindhunter, they can be used to identify the killer and, potentially, his or her other crimes.

The MO
English: A crime scene. MO and Signatures
English: A crime scene. . (Photo credit: Wikipedia)

The MO is the way a crime is committed. The tools, the method or location for example. A well as habits and peculiarities. A modus operandi does not only apply to murderers. Whether the crime is burglary, arson, embezzling, or murder, the perpetrator will have a particular way of doing things.

The perpetrator uses particular behaviours, tool, habits, etc. to commit the crime, get away, and with a bit of luck evade capture.

All crimes have a modus operandi but not all have a signature.

The Signature

The Signature is the personalisation of the crime scene after the fact. This could be staging the scene so the body or object is in a specific location or the mutilation of the body itself, post-mortem, in a specific way. It could even be leaving behind an additional item that has a meaning for the perpetrator and could point to the motive. A signature is an emotional or psychological satisfier.  Unique to the perpetrator.

  • Randy Kraft – mutilation, eye removal, scorecard
  • Charles Albright – eye removal
  • Ted Bundy – Feigning Injury to lure victims
  • Leonarda Cianciulli – making soap out of limbs & skin, and cakes with the blood

Would you like a Cup of Tea with that?

If we think of an MO and signature in terms of behaviour rather than being specifically related to a crime scene then you can see how it’s a natural part of human behaviour. And the investigators take advantage of this to help find the perpetrator.

Take making a cup of tea for example. Your MO is the way you make the tea. Whether you brew it in a pot or a cup, with a bag or leaves. The signature would be what you do to the tea afterwards. Perhaps you like milk or lemon, a spoonful of sugar or a sweetener. It could also be in the way you stir it, three times clockwise and three taps on the edge of the mug.

Evolution or change in MO

This is often heard in films and TV shows where the main storyline features a serial killer. Often allowing them to look back at old crimes with early signs of the pattern and see the evolution in the current crimes. The evolution or change in an offender’s MO occurs as they improve their technique or become more proficient. The longer they go uncaught the more time they have to perfect their modus operandi.


CRIME SCENE DO NOT CROSS / @CSI?cafe (Photo credit: Wikipedia)

[Updated: 16/03/2018]