We are talking about forensic profiling, where psychologists and behavioural scientists will use science and experience to try to develop a profile of a criminal. They will use information gained through research and study. Research has found that the following factors can influence who commits a crime.
Gender
In the Western world, nearly 90% of murders are committed by males. Males are also the victims in nearly 75% of murders.
Age
Age also affects murder rates, there is an increase in murders between the ages of 17 and 30. People are less likely to commit murder as they age, but murders committed by children and adolescents are also rare. However, if we look at research across different countries and cultures, the patterns do not always appear similar. For example, in Korea, according to the Asian Correspondent newspaper, 37.4% of murderers are men, which is obviously less than in America. But all of the criminals had committed their crimes in their 30s.
Relationships
We often watch movies and TV programmes where we think it is going to be the spouse who did the murder. But the Crime Prevention Research Centre in America found that –
- 9.4% of murders were committed by a husband, wife, common-law husband or wife, father, mother, son, daughter, brother, sister in law, step-father, step-mother, step-son or step-daughter.
- 1.8% were other family members.
- 4.2% were boyfriends, girlfriends, ex-husbands or ex-wives
- 14% were acquaintances. This is a broad category can include taxi drivers to prostitutes and their customers.
- 3.1% was a friend
- 5.4% was other known
- 11% a stranger
- 39% was a unknown relationship. For example, they were involved in a gang fight but there was no apparent direct relationship between the victim and murderer.
- 1% a neighbour
But even looking at these statistics, it is not quite so clear cut. With family murders, the murderers tended to also have a criminal record for other crimes, so it is not just a simple case that someone in the family murdered the person.
Mental Illness
There is often a misconception that people who commit murder are mentally ill in some way. However, this is not always the case. The Asian Correspondent reported that 81.3% of Korean murderers had no particular mental illness. 3.9% suffered depression, 0.7% had a mental illness. Time to Change in the UK reports that the majority of murders are committed by people who do not have mental health problems. They estimate that there are 50 – 70 murders per year that involve a person with a mental health problem at the time of the murder.
It also depends on the type of mental illness you are discussing.
Some terms used in psychology are as follows:
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Antisocial personality disorder
(also known as sociopathic personality or psychopathic personality)
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A personality disorder that usually begins in childhood or the early teens. There is a lack of remorse and a disregard for punishment.
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Delusion
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A delusion is a false belief or opinion. The person may believe that the belief is an actual fact. For example, the person may believe that they can control others with their mind. Or they may have delusional jealousy, believing that their partner is having an affair.
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Hallucination
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A sensory experience of something that does not exist outside the mind. It can be caused by physical or mental disorders. Hallucinations are usually auditory or visual. For example, a person may hear voices.
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Narcissist
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The person will be fascinated with themselves, they will be vain and have excessive self-love. The “God Complex”, which can be found in rapists and serial killers.
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Psychopath
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A person with a chronic mental disorder. They will have violent or abnormal social behaviour.
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Schizoid
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A personality disorder where the person is dissociated, passive, withdrawn, indifferent to praise and criticism and unable to form warm social relationships.
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Schizophrenia
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Schizophrenia is a severe mental disorder, which leads to intellectual deterioration, negative affect (a lack of observable emotion), social isolation, disorganized speech, delusions, hallucinations. Whilst we are mentioning this here, research does suggest that the link between schizophrenia and crime is low. Research in 2002 by Walsh et al found that there is a higher level of violence found in people with schizophrenia. BUT the level is still very small, less than 10% of violence. They found that “Most studies confirm the association between violence and schizophrenia. Recent good evidence supports a small but independent association. Comorbid substance abuse considerably increases this risk. The proportion of violent crime in society attributable to schizophrenia consistently falls below 10%.” And this does show that additional substance abuse increases the risk substantially, so support with drug misuse could help reduce this.
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Sociopath
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A person with a psychopathic personality. Their behaviour is antisocial. They lack moral responsibility or a social conscience. This trait is often seen in serial killers.
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If you are interested in learning more about psychology and behaviours take a look at our new short course Behaviour Profiling
or, look at our 100 hour courses:
Psychological Assessment BPS308
Criminal Psychology BPS309