When detectives are investigating multiple murders, one of the most important questions they ask is whether the crimes are connected.
The answer can be found in the details.
Here are five things investigators may examine when looking for a killer’s pattern.
1. Victimology
Who are the victims, and what do they have in common?
Detectives examine their backgrounds, routines, relationships, workplaces, locations, and other circumstances to determine whether there is a reason these particular people were targeted.
2. Modus Operandi
A killer’s MO, or modus operandi, refers to how they commit a crime.
Detectives may compare how victims were approached, how the crime was carried out, and other practical details. An offender’s MO can change over time, so investigators look for meaningful similarities rather than expecting every crime to be identical.
3. Signature
MO and signature aren’t the same thing.
An MO is about what the offender does to commit the crime. A signature can involve behaviors or details that aren’t necessary to commit the crime but may reflect something distinctive about the offender.
When unusual details appear across multiple cases, detectives take notice.
4. Connections
Once detectives start comparing cases, they look for connections.
Are the victims connected? Did the crimes happen in similar locations? Are there similarities in the evidence, timing, or circumstances?
One similarity may mean very little. Several meaningful connections can point to a much larger pattern.
5. What Doesn’t Fit
Investigators also have to consider what doesn’t fit.
A good detective can’t simply decide that two crimes are connected and ignore evidence that says otherwise. The pattern has to be supported by the evidence.
Sometimes the detail that doesn’t fit is the one that reveals the truth.
The Pattern Can Change Everything
Identifying a killer’s pattern can turn separate investigations into one much larger case.
That’s one of the things I love about writing crime fiction. The investigation isn’t just about finding a suspect. It’s about following the clues, recognizing connections, and figuring out what the evidence is really saying.
Because sometimes, the smallest detail is the one that connects everything.
