Mindhunter: Inside the FBI’s Elite Serial Crime Unit

Also known as MO, a modus operandi is dynamic in nature. According to John Douglas, it is learned behavior and can evolve over time. An MO is what an offender does to commit the crime. If s/he gets away with committing the first crime, they will learn from the mistakes of the first offense and change to get better at what they do. 

A signature is what the offender uses to express his desires and impulses, and it is a term coined by Douglas. A signature is static, and it can be subtly different from MO, but it cannot change even if the offender is aware of it. A signature is not necessary for the commission of the crime. An example of a signature would be the deliberate posing of the victim’s body in a degrading manner after the commission of a homicide.

Staging is the word to describe an offender’s attempts to change the crime scene to make it appear as though something else happened. An example of staging would be an attempt to change a murder scene to resemble the scene of a suicide or an accident by moving the body or cleaning parts of the crime scene.