The spatial behavior of residential burglars Manuel J.J. ... - TU Delft

432 Manuel J.J. López
our crime series, we see that 4 out of 20 offenders committed residential burglaries on the
street where they lived. Two offenders even committed burglaries in the homes of their
former neighbors. These facts are not in line with the theories that assume the existence
of a buffer zone.
7. Travel direction
By only looking into the offender’s range of operation, distance decay, and buffer zone,
we make the implicit assumptions that offenses are evenly distributed within the range of
operation and that the home of the offender will be exactly in the middle of the offence
locations. We have seen however, that these assumptions are not correct. The offender’s
home address is often not exactly in the middle of the offence locations and some distances
contain more offences than others. This can be caused by the non-random distribution
of opportunity spaces, but it can also be caused by the fact that burglars have some
favorite travel directions, for example, because the locations of their work, recreation
and/or shopping happen to be in those directions. The presentation of Akkelies van Nes
will deal with the possible influence of the built environment (and the related distribution
of opportunity spaces) on the offender’s spatial behavior. First, however, we will take a
closer look into a possible alternative explanation; namely the offender’s preference for a
certain travel direction.
According to Lundrigan and Canter (2001), the hypothesis about the offender’s directional
preference can best be tested by analyzing the angles created by the offender’s
home and his offence locations. The hypothesis is confirmed when the angle is smaller
than 90o (a sharp angle). If the angle is bigger than 90o, we must reject the hypothesis. In
that case, we have found proof that the offender does not have any directional preference.
Godwin (2000) follows a comparable approach and calculates the directional angle on the
basis of the geographical degrees of longitude and latitude. Both studies show that serial
killers and (in the case of Godwin’s study) serial rapists have a clear directional preference
when committing offences. This is important information for geographic profiling, since it
aids in restricting the size of the search area.
However, residential burglars are (in most cases) not serial killers. And we have seen
that some aspects of the spatial behavior of offenders (e.g., travel distance) are influenced
by factors that are related to the offence type. For this reason, we should not automatically
assume that conclusions about the directional preference of serial killers and serial rapists
also apply to serial residential burglars. At present, there is no empirical evidence that
proves that residential burglars do or do not have a directional preference. The study from
Barker (2000) seems to suggest such a preference, but provides insufficient evidence.
When we apply the method of Lundrigan and Canter (2001) and calculate the directional
angle of the crime series, we see that the residential burglars in our sample do not
have a preference for a certain travel direction. There is only one crime series in our sample
with a directional angle smaller than 90 o . This relatively small angle (35 o ), however,
seems to be the result of the small number of offences in the crime series rather than the
personal preference of the offender for a certain direction. Nine of the 17 crime series even
show angles of 180 o or bigger.