The document discusses the differences between a murderer's modus operandi (MO) and signature. The MO refers to the behaviors used to kill the victim and get away with the crime, such as restraints or tools. The MO is likely to evolve over time as the murderer experiments. In contrast, the signature is not necessary to commit the crime but fulfills a psychological need for the murderer. Signatures rarely change and can include posing victims or adding objects to the crime scene. Careful evaluation of both the MO and signature is important for profiling a serial killer or other murderer.

1. How Murderers' Signatures and
MOs Differ
By: Dr. N.G. Berrill

2. How Murderers' Signatures and MOs Differ
For more than 30 years, Dr. Naftali Garcia “N.G.” Berrill has been practicing as both a clinical and
forensic psychologist. The executive director of NY Forensic, Dr. Naftali G. “N.G.” Berrill has
completed numerous interviews on topics relating to everything from personality profiling and law
enforcement consulting to serial killers and other violent criminals.

3. How Murderers' Signatures and MOs Differ
When creating a profile of a serial killer or other murderer, there must be careful evaluation of both
the killer’s modus operandi (MO) and signature. Though these both appear at the crime scene and
are part of the killer’s behavior, they are two distinct parts of a murder.

4. How Murderers' Signatures and MOs Differ
The MO refers to how the killer took the life of another. It encompasses any behavior they feel is
necessary for accomplishing or getting away with their crime. This may include the type of
restraints used on the victim, the tools that helped the offender gain access to the victim’s home,
the time of day that the crime was committed, and the perpetrator’s alibi. It is possible for the MO
to remain the same over the course of several murders, but this is unlikely since a murderer’s MO
evolves over time as they become more comfortable or familiar with different methods.

5. How Murderers' Signatures and MOs Differ
Conversely, the signature is not necessary for getting away with or completing the crime. Rather, it
has some personal significance to the murderer, and fulfills a psychological or emotional need. If
present in a crime, The signature rarely changes, though it could be refined over time. Aspects of a
killer’s signature includes posing the victim or victims in a specific way, adding ceremonial objects
to the crime scene, or injuring the victims far beyond what’s necessary to take their life.