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5. Unusual previous offences
UNUSUAL PREVIOUS OFFENCES
This chapter considers in more depth those convicted of murder or SSA who had
less common offences in their background. In particular, it focuses on those previous
offences for which less than two per cent of either murderers or serious sexual
offenders had convictions, but which were nevertheless statistically significantly
different from the controls. Of course, the very nature of ‘unusual’ offences means
that the number of cases is often limited and this needs to be considered in assessing
the inferences that follow.
Offenders convicted of murder
Using the criteria for ‘unusual offences’, it was found that convictions for
manslaughter, kidnapping, blackmail, soliciting by a man and adulteration of
food/drugs significantly increased the relative risk of murder. Manslaughter was the
most clear-cut and perhaps most predictable. The possible links between
kidnapping, blackmail, soliciting by a man and adulteration of food/drugs with
subsequent convictions for murder are more intriguing, and several of these are
examined in more detail.
A previous conviction for manslaughter was shown to be statistically significant for
murder (see Table 6), and those with such a conviction are over 19 times as likely to
be subsequently convicted of murder. Five murderers and one general control had
manslaughter in their history. As there were approximately four controls to every
murderer, it would be expected that if cases and controls were similar, there would
be around 20 offenders with manslaughter convictions among the controls.
However, a conviction for manslaughter did not significantly distinguish murderers
from violent controls.
A previous conviction for kidnapping was shown to be a statistically significant risk
factor for murder, both when compared against general criminal controls and against
violent controls. Focusing on the offender-victim relationship reveals that
kidnapping is only a significant risk factor for subsequent male stranger murders. In
fact, of the six murderers with a previous conviction for kidnapping, three had
murdered a male stranger (of the others, two had murdered a male acquaintance and
one had murdered a female stranger). There is no evidence that anyone with
kidnapping in their history murdered a family member. Furthermore, for all cases,
the murder conviction was within six years of the kidnapping conviction.
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