Describe what is meant by 'bottom up' and 'top down' when applied to offender profiling'. Offender profiling is a set of techniques used to try and identify perpetrators of a serious crime. Offender profiling will tend to use the expertise of a professional psychologist, although profilers come from different types of backgrounds because there is no specific training for the job. The profiler will draw on his knowledge of personality theory to attribute personality traits to the offender. The profiler will consider many elements when carrying out a profile, such as the crime scene, the offence, the sex of the victim and offender, body deposition site and the interaction style. These are just a few of the issues the profiler will consider.

There are many different definitions of offender profiling today; according to Turco (1993) offender profiling is 'the preparation of a biological sketch, gathered from information taken at a crime scene, from the personal history and habits of a victim, and integrating this with known psychological theory'. However, other psychologists are much more sceptical of offender profiling, for example according to Harrower (2000), offender profiling is seen as the sexy speciality of forensic psychology largely as a result of Fitz in Cracker (TV drama). But the poetic license allowed in that TV series hasn't been particularly helpful to psychology as a discipline'. Offender Profiling is popular both in the UK and the USA, but like many things the UK and USA use their different methods. The USA uses what we call a 'top-down' approach and the UK uses a 'bottom-up approach', which contrast quite significantly.

The 'bottom- up approach' is where information is gathered and conclusions are drawn strictly from the evidence, with previous knowledge or experience not being used. Boon and Davies (1992) suggested that the British approach to offender profiling is 'bottom up' as the profiler only uses information gathered from the scene of the crime, and information about the crime itself, and from this information a picture of the criminal is suggested. Conclusions are tentative, being formed from what has been observed. In the UK a psychologist called David Canter who works at Liverpool University dominates offender profiling.

It was while at Surrey University, he was asked by the Metropolitan police if he could help them, or tell them anything about a serial rapist, who was later found to be a serial murderer. David Canter gave a remarkably accurate profile of the killer John Duffy, who was convicted in 1988 of the rapes and murders. Canter further suggested that criminals, like all people act in a consistent way and that all actions are linked no matter the setting, and therefore an analysis of their behavior can offer clues as to their lifestyle during a non-offending period, thus aiding possible detection and arrest. Canter thought that because people live in a social context there would be an implicit relationship between offender and victim, which could also help to offer clues to the offender's life. Canter's approach to offender profiling is much more scientific than that of the FBI's, as it based more on psychological theories and methodologies.

Canter thought criminals left certain psychological traces after committing a crime; '... tell-tale patterns of behavior that indicate the sort of person he is. Gleaned from the crime scene and reports from witnesses, these traces are more ambiguous and subtle than those examined by a biologist or physicist... They are more like shadows which can indicate where investigators should look, and what sort of person they should be looking for'.

(Canter 1994) Canter believes the way he can help police in investigations is by using sets of data to look at correlation's between things like time and location of offence, choice of victim, and analysis of speech, and develop trends and patterns. Canter claims this method is more valid than sensational interviews whose validity is suspect. Canter has lead to the arrest and convictions of very dangerous serial killers such as John Duffy and serial rapists such as Adrian Babb, along with other offender profilers such as Paul Britton. When making a profile for the police, Canter found that interpersonal coherence between the offender and victim is an important factor, this means for example how violent the offender was in a rape, in that was he apologetic or was he very abusive and controlling. This may reflect the way the criminal treats other women, in his non-criminal life.

Also the type of victim may also reflect the sub-group to which the criminal belongs. For example Ted Bundy killed over 30 students, when he himself was a student. The time and place of the crime may also be significant when making a profile. The precise location of the crime and the map of the relationship between the places in which a series of offences took place, may relate to where the offender is living and to his past experience. Forensics are important when making a profile. For example if a rapist has been questioned previously by the police, their crimes may leave indications of this, this can be shown by some rapists who make their victims bathe to get rid of forensic evidence, so a check of police records is always worthwhile.

According to Boon and Davies (1992) Canter and his colleagues identified five aspects of criminal behaviour which is very significant and revealing; the location, criminal biography, personal characteristics, domestic and social characteristics and occupational history. Another important aspect is geography, where criminals may feel comfortable committing the crime. By contrast the 'top down' approach to offender profiling, involves using previous knowledge and information to draw conclusions about a current situation, and is reliant on subjective conclusions that come from investigative experience of crimes and criminal interviews. The American method of offender profiling is called a 'top-down' approach. The FBI and its behavioural science unit have received much attention compared to Canter and Britton through the years, possibly due to fictional films and characters such as Agent Starling in 'The silence of the lambs', although these movies do not illustrate the real aspects of offender profiling.

In the USA, the NC AVC (National Center for the Analysis of Violent Crime) is responsible for handling around 1500 cases a year, and helped convince the UK to make a profile to catch the Yorkshire Ripper. In 1970's USA there was a huge increase in the number of murders and rapes, the work of serial killers such as John Wayne Gamey, David Berkowitz and Ted Bundy. In 1979 the Behavioral sciences unit (BSU) was set up, initially a team of 9 whose task was to continue the work pioneered by James Brussel, the profiler who produced a very accurate profile of 'the mad bomber'. The BSU started by building up a library of interviews with the countries worst convicted serial killers and rapists, including Charles Manson and Ted Bundy. From this the BSU gained a valuable insight into the mind of a killer and became known as 'the mind hunters'. Also the collection of detailed information from the BSU who were experienced in the area of sexual crime and murder, was combined with the interviews to give psychological clues and predictions to the crime, for example the age of the offender, marital status and the occupation of the offender.

The FBI then developed a classification system for serious crimes, where by murderers were classified as organised, meaning they are very meticulous, planning their crime very well and leaving no forensic evidence, usually intelligent, have skilled jobs, probably married and are sexually competent. It is quite possible they acted out this crime when they was angry or depressed, maybe affected by reports of crime in the media. In contrast, murderers could also be classified as disorganised, meaning the crime was very unplanned and haphazard, therefore more likely to leave clues. Disorganised murderers are more likely to be unskilled, socially-inadequate individuals, with sexual problems and at the time of the crime would probably be frightened, as it is more likely they know the victim. After this classification system was established the FBI detailed what should happen when a serious offence occurred, outlined by Jackson and Bekerian (1997): Data assimilation is the first stage where information from as many sources as possible is collected, such as photographs of the scene of the crime or letters etc. Then the crime has to be classified, where the crime is put into a particular category based on the data collected.

The third stage is crime reconstruction where hypotheses are developed about the behaviour of victims and the modus operandi of the criminal based on a reconstruction of the crime. Finally a profile is generated about the perpetrators physical appearance, demographic characteristics, habits and personality. The use of previous knowledge is why the American approach is referred to as 'top-down', although nowadays the approach is more rigid and profiling is likely to include intuition and investigative experience. According to Holmes (1989), the aims of profiling in this approach are to reduce the scope of an investigation by providing social and psychological information about the offender's personality, allow some prediction to future offences and their location, provide a psychological evaluation of any belongings found in the offender's possession and to provide strategies for interviewing offenders.

There are differences within the two approaches which make it hard to be precise about the differences between 'bottom-up' and 'top-down approaches to profiling. For example in the UK Paul Britton makes a profile using both evidence from the crime scene and likely behavioural patterns of the offender. Canter uses evidence from past crimes, which may be seen as 'top-down', but he mainly collates his data from empirical, 'bottom-up's our ces. David Canter argues that relying on interviews of convicted murderers is not sensible, as serial killers are known to be manipulative and sensation seekers, although nowadays profiling in the USA uses information from the scene. The FBI now trains profilers worldwide, and have found that profiling is most useful when there is evidence of psychopathology. There is no doubt that Canter's work and approach to profiling owes more to psychology than that of the FBI.

According to Canter the FBI's type of profiling is 'more of an art than a science'. (Canter 1995) In the UK Cops on and Holloway (1997) surveyed detectives who worked on 184 cases in which offender profiling had been used. They believed it had produced identification of offenders in less than three per cent of cases and helped to solve the crime in 16 per cent. They concluded 'profiling can work very well, but certainly not in the way some practitioners, or dramatists would have you believe.

There is nothing in our findings to support the notion that complex offender characteristics can be predicted with any great accuracy. In fact with some people you would be better off tossing a coin'. In contrast, according to Harrower (1998), offender profiling has undoubted potential if used properly by trained professionals, as in the USA '192 cases of offender profiling led to 88 arrests'. However the aim of both the British and American processes is to identify areas that will help in the investigation leading to arrest of the offender, and it is clear that when both methods are combined together, the more likelihood of catching an offender there is.