What Is Modus Operandi?

While watching your favorite crime drama on television such as CSI or Law & Order SVU, you might hear your favorite detectives tossing the phrase “M.O.” around. But what exactly does this mean?

Modus operandi is a Latin phrase which translated means “operation method”.  This phrase usually refers to a distinct pattern and/or a particular way of working for a criminal when they are committing a crime. Regardless of the crime, whether it be a burglary, sexual assault or even a white-collar crime like embezzling, the criminal performs the crime in a particular way.

This is not to be confused with a criminal’s “signature”. A signature is a personal mark or imprint after the crime is committed.  All crimes have a modus operandi, but not necessarily a signature because a signature is not required to commit a crime but rather serves as a psychological or emotional need for the criminal.

This is also different than the motive of the crime. The motive of a crime is the reason as to why the crime is being committed not the way in which it was perpetrated.

An M.O. can be something simple such as he preferred to shoot the victims with a gun to something very complex like Jeffrey Dahmer’s modus operandi:

  1. He would frequent gay bars waiting for the opportunity for a victim to appear
  2. He would get intoxicated
  3. He would invite an unsuspecting male back to his abode (for various reasons)
  4. Once at their apartment, he would mix a drink with sleeping pills which would make the victim unconscious in a half hour.
  5. He would begin having sex with the victim before and/or after they were unconscious
  6. Once drugged, he would strangle the victim causing their death
  7. Once dead, he would continue to have sex with the body in various ways
  8. He would take pictures of the dead body.
  9. He would dismember his victims (continuing to take pictures along the way)
  10. He would dissolve the body with acids and flush it down the toilet

Many police and detectives rely on the M.O. to help connect crimes that might at first glance appear to not related because their victims might be of different ages or in different geographical locations.