When law enforcement officers do not have much evidence needed they sometimes request the help of a forensic psychologist. Using the gathered evidence and knowledge they then start creating what is known as an offender profile.
Offender profiling in definition is known as "an investigation tool that aids in the identification, apprehension and conviction of an unknown offender by providing the police with a description."
Advantages of using this are that it also helps to see the type of people the offender is targeting and who could be the next victim, where and when. But of course they are some limitations, offender profiles are only as good as the information provided to the profiler, therefore this leaves room for mistaken identifies. It should not be the only method used by the authorities.
They are two ways to this -The American Approach - Using the data that would have been gathered the law enforcement officials can determine the offenders lifestyle or personality characteristics. From this they will be able to determine if it is a organized or disorganized offender. Also known as the top-down method because is aims at understanding and classifying the crime details based on already existing categories (typologies).
The second method is the British approach or investigative psychology also known as the bottom- up. It starts with small or little details and they aim to build or connect the dots into a bigger picture. No prior assumptions are made and this approach relies immensely on computer databases. It is the little details that are often overlooked but are quite crucial to understanding and having a breakthrough in a case.