(NOTE: these techniques and assumptions are used in my teaching to teach personal adjectives. Criminal Profiling and Handwriting Analysis should be done by experts, this article is only to raise interest in these fields and describes them in a simplistic manner.)

Criminal Profiling has been with us since the 1970s, at least the one that the FBI conceptualized by conducting a series of interviews with serial offenders. However, the notion of profiling goes beyond that: in the 1940s and 1950s, George Metesky – also known as ”the Mad Bomber” – planted several bombs in New York City until a criminologist and a psychiatrist provided a profile of the offender, which eventually led up to his arrest in 1957. Years later, FBI agents Howard Teten and Robert Ressler Were preparing the information on Ted Bundy based on his MO (modus operandi or method of operation) and Bundy’s capture was definitely a milestone in criminal profiling. 
The numerous movies and series have all been focusing on the criminal profiling as an investigative strategy, but rarely do they focus on the “messaging”: the way people, and thus serial killers write can tell us and the detectives some information on the personality of the author. We have known about serial killers who wanted to contact the police – think of the Zodiac Killer or the BTK-killer – and although it would be harder to decipher some codes or messaging, handwritten letters can contain some information.    
As a possible part of criminal profiling, handwriting analysis (HWA) focuses on these vital pieces of information based on such principles, as “Spacing” or “slanting”. For the sake of simplicity, we will focus on these two a little bit more. It is a well-known fact that in some cultures, people write from the left to the right, meaning that the “top-left” part of their text represents the past and the “bottom-right” part represents the future.

The concept of time in HWA

One should also focus on the spacing between lines and letters, as they can show how patient/impatient a person can be – for instance. However, other personality traits might be found in handwriting: slanting (= the way each letter leans) is likely to be a representative of an author being reserved, careful or even impulsive. These signs in writing can be determined based on slanting, as there are three types of it: forward slant, vertical slant and backward slant. Aileen Wuornos – the US serial killer – had a forward slant and her impulsiveness supported her handwriting style. Gary Ridgway, another US serial killer, had a vertical slant, making him a careful predator when on the prowl. We have an “odd-one-out”, the mass murderer, Timothy McVeigh, who used to have a backward slant style in his handwriting, and his reserved personality checked it out.
These methods are worth taking into consideration when dealing with criminal profiling, as they can contribute to a better picture of the perpetrator. The techniques of profiling complement the ongoing investigation, and not substitute it, as some might falsely assume.

Credits to Macel Elfers.