Personality typing has been used in recent years, especially in the USA, to help detect certain types of criminals. It has been particularly used in cases involving serial murders. Note that serial murder is not simply mass murder which is the killing of a number of people in a relatively short space of time and small geographical area, eg Hungerford and Dunblane.

Mass murders occur from one outburst and often conclude with the suicide of the perpetrator. The victims are chosen by chance and the outburst is caused by a sudden, uncontrolled mood change.

In contrast, serial murder is a repetitve event. The murders take place over months or years in different locations. The murders involve only one victim at a time and they are generally complete strangers. Such murders are often accompanied by sadistic acts, mutilation or both. To many, these murders appear to be without any reason or motive: the acts of a mad man.

Holmes and De Burger (1989) claim such a description is not correct. They assert that such murderers are not suffering from any mental illness and that there is a motive. Neither are the murders the result of purely uncontrollable urges. In terms of motive, one does exist although to most people it seems irrational. The motive, they claim, is internal not external. That is to say, it is not linked to financial gain or belief in a cause. The motive stems from the pleasure of killing. Sometimes other motives are linked to the need to eliminate certain categories of person: prostitutes, tramps, young women etc.

Another motive might stem from the feeling of power over the victim. In any case, the motive is an inetrnal one inside the murderer.

K S Williams makes a distinction here between sociopaths and psychopaths. Aggression and antisocial behaviour in this case is generally caused by environmental factors and is linked to a sociopathic personality type. The illness of psychopathy is distinct - see later.

Sociopaths are described as being asocial (unsocialised) and therefore feel no guilt at breaking the rules of society. They are diven by selfish, powerful and uncontrolled desires which require immediate gratification. The sociopath is often aggressive and impulsive. Not every serial murderer will fit with all aspects of such a description. There may be some variations.

The origins of this personality type may be numerous and sometimes disputed. Certain commentators believe a person is born with the possibility of acquiring such a personality. Note, however, that all accept that upbringing, especially relationships with parents and the amount exposure to violence as a child, has a major impact on their development.

Holmes and De Burger categorise serial murderers into 4 main types:

- Serial murderer kills because 'commanded' to do so by voices or visions (Peter Sutcliffe & murder of prostitutes).

- rarest type of serial murderer. Perhaps suffers from psychotic mental problem and out of touch with reality.

- victims tend to be strangers and seen as part of target category of persons.

- killing is spontaneous and disorganised.

- murderer has a goal (to rid world of certain type of person) but goal comes from within not in response to voices.

- murderer not psychotic but needs to solve a particular problem.

- aware of what he is doing and knows that action is wrong and is condemned by society for it.

- appears normal to people and often successful.

- chooses groups seen as 'unworthy' (protitutes, tramps etc)

- act is well planned and victims usually strangers.

3. Hedonistic Type

- Person kills for pleasure.

- two types: 1. thrill-oriented killer and 2. lust killer

- thrill-oriented killer: enjoyment at excitement of killing. Victims strangers chosen randomly with no particular characteristics. The murder is spontaneous and disorganised. Sometimes element of sadism.

- lust killer: central element of crime is sexual. Sexual pleasure increased by amount of pain and mutilation inflicted. Gratification gained by abuse of victim. Usually lead normal lives with normal relationships except of problem of sexual gratification. Lead-up to crime part of the pleasure. Victim usually a complete stranger. Act usually planned.

Difficult to distinguish from lust or thrill-seeking type. Same traits. But criminal act based on desire to show total control over other human being. Power is main factor behind crime. Sometimes sexual abuse of victim but only really to demonstrate power. The killing is often sadistic.

The above is only a generalisation of these types of criminals. The characterisation for the purposes of a crimianl investigation has to be more precise. For a full profile other details such as the scene of the crime, type of person victim was, physical appearance and so on are necessary.

Psychopathy is a severe personality disorder and is oftern considered to be potentially extremely dangerous. Section 1 (2) of the Mental Health Act 1983 defines psychopathic disorder as:

'a persistent disorder or disability of mind....which results in abnormally aggressive or seriously irresponsible conduct on the part of the person concerned.'

The disorder must have existed for some time so that it is classified as persistent. In terms of what is 'abnormally aggressive' or 'seriously irresponsible' is not defined and is left for the court to interpret with the help of pyschologists.

Offenders are dealt with under s37 of the Mental Health Act 1983, which allows them to be admitted to mental hospital rather than be sentenced to a punishment. Note that the Report of the Committee on Mentally Abnormal Offenders (1975) stated that the long-term effect of punishing psychopaths tends to be that they become more antisocial and vindictive.

Psychopathy does not neccesarily involve any damage to the ability to reason. Such people may be aware of their actions and surroundings. Rafter (1997) states that the term 'psychopathy' is extremely difficult to define in terms of a personality defect. It has more validity in terms of mental incapacity.

A psychopath normally sffers from distortions of feelings and affections as well as possessing strange habits, desires and moral dispositions. He will display odd behaviour such as frequent mood swings and temper, violent outbursts and impulsive behaviour. The psychopath is unpredictable, unresponsive to help.

Hare (1980) suggests 5 elements which describe the psychopath:

1. an inability to develop warm, responsive and affectionate relationships, a general lack of empathy;

2. an unstable lifestyle;

3.an inability to accept responsibility, especially for their own behaviour;

4.they do not have psychiatric problems nor are they unintelligent;

5. they have problems in controlling their behaviour.

In a publication by The Department of Health and Social Security and Home Office in 1986, pyschopathy was described as:

'The core problem is impairment in the capacity to relate to others - to take account of their feelings and to act in ways consistent with their safety and convenience.'