We've often heard of the 80/20 Rule. In law enforcement, the rule says that 80% of your crime is committed by 20% of your offenders. While the exact percentages are probably not 80/20, it is safe to say that a significant amount of the crime in your jurisdiction is committed by a minority of offenders.
It would also be nice of these prolific offenders if they would identify the crimes they are responsible for. It would make linking them together a whole lot easier. We can't expect offenders to leave their business card on the door or to sign their work. But in one way, they do. Often times, their "Modus Operandi" can link them to the offenses they're responsible for.
So just what is Modus Operandi? The phrase is Latin for "method of operation". Often times we hear it when referring to serial killers or some other exotic crime. But it doesn't just apply to exotic crimes, every crime and every criminal has a modus operandi or M.O. A criminal's M.O. can help you determine what crimes he or she is responsible for.
A prolific offender often develops an M.O. over time. Criminals will learn as they begin committing crimes. As they become more successful and more comfortable in committing offenses, they will usually stick with what works for them.
Economic principles also apply to offenders. If they have to spend more time and effort to commit a crime than the payoff, they will eventually abandon that method and seek out one where the economics are more stacked in their favor. They will learn from others in their social circles or even through trial and error. Eventually, they will gravitate to something that works.
If your agency faithfully records M.O.'s in your offense reports, you can use this data to identify offenses that can at times be attributed to specific offenders or groups of offenders. An offender identified in one case, can be linked through M.O. to another case where he or she was not known.
I worked on a serial armed robber whose M.O. allowed us to tie him to quite a number of armed robberies. He wore similar clothing during each robbery, he targeted similar businesses and made specific comments to the victims in each crime. At the beginning of the series started targeting these businesses in the late evening hours. However, he shifted to hitting businesses during the early morning hours and was more successful. By reviewing armed robberies in our jurisdiction and in neighboring jurisdictions we were able to pick out crimes he was responsible for because his M.O. had been unique and had been recorded.
It's important to try and identify as many crimes in a crime series as possible because the more information you have, the more likely you are to develop enough information to be able to solve a crime series. In fact, if you identify enough crimes in a series you can then start to predict future incidents based on statistical techniques such Mean Days Between Hits or other more sophisticated analysis.
Here are some general M.O. areas you need to try and cover in your analysis.
- Journey to crime scene
- Method of entry and entry point
- Actions inside
- Weapons used
- Words to victim
- Actions towards victim
- Items taken
- Method of exit and exit point
- Flight from crime scene
It's important to encourage your officers to gather M.O. information carefully during the initial investigation. You can further this end by taking opportunities to develop training materials that provide information on gathering M.O. information and sharing success stories where analysis of M.O. was important.
It's also important to identify known offenders associated with particular M.O.'s. If their M.O. is unique enough, and you begin to have a number of crimes with that or a very similar M.O. this will give you a place to start on the suspects list. For instance if you know a particular offender is associated with rooftop business burglaries, then you can start looking at him a bit harder when you start having a rash of rooftop business burglaries.
Another often times fruitful endeavor is to debrief offenders about their M.O. or their knowledge of other criminal's M.O.'s. If your detectives can develop a rapport with an offender you can learn a lot from a good thorough debriefing. Questioning them about their M.O. can give you insights into their target selection allowing you to develop information that can guide further investigations or crime prevention efforts.
How does your agency collect and analyze modus operandi information?