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6. Summary and conclusions
SUMMARY AND CONCLUSIONS
Much of the previous work on the risk of offending behaviour has focused on
recidivism (i.e. the likelihood of re-offending behaviour). This study has instead
focused on the likelihood of those within the general criminal population of
committing their first serious offence (murder or SSA of an adult female, including
rape). This chapter summarises the rationale for the study, explores what lessons
may be learned and finally discusses some of the practical applications the research
might have.
Having an understanding of criminal histories is important for many of those working
within the criminal justice system. There has, of course, been a long tradition of
criminological work in using criminal histories to predict re-conviction and reoffending.
This tradition, which began with the pioneering work of Ernest W. Burgess
in Chicago in the 1920s trying to identify those who would be most appropriate to
parole (Mannheim, 1965), has evolved. In the late 1990s, the Home Office developed
the (revised) Offender Group Reconviction Score (OGRS). This is a statistical risk
score which provides an estimate of the probability that a convicted offender will be
re-convicted at least once within two years of release from custody or from the start of
a community sentence (Copas and Marshall, 1998; Taylor, 1999). The Offender
Assessment System, a new national system for assessing the risk and needs of an
offender, represents the most recent development in this area (Home Office, 2001).
This present study, however, has examined whether it is possible to look back at
criminal histories to reveal something more specific about the future. It started with
the idea that a more systematic study of the previous criminal history of those that
had been convicted and sentenced for murder or SSA might provide an insight into
patterns in very serious offending behaviour.
The approach involves the language of probabilities rather than of certainties: what
is the relative risk of those committing certain types of crime in the past becoming
murderers or convicted of SSA? It is important to remember the general weaknesses
around using conviction data as proxy for offending behaviour; through the process
of attrition, successful convictions represent only a proportion of all offences
committed. Moreover, this relationship varies considerably between the target
offences of murder on the one hand, and rape/serious indecent assault on the other,
as well as in relation to all the prior offences that make up criminal careers.
Notwithstanding the problems around using conviction data as a proxy for
offending behaviour, using appropriate control groups does produce analytical
rigour. It is of little use knowing that over 40 per cent of convicted murderers have
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