another leading researcher in this area is david canter whose approach to geographic profiling detailed around the circle theory of environmental range. in 1993, canter and larkin developed two models of offender behaviour: marauder and commuter models. the distinction is that marauders operate in an area that is in close proximity of the offender's home base while commuters commit crimes far outside of the habitual zone. it hopes to differentiate the two types of serial offenders by studying the relationship of the criminal spatial behaviour to the offender's place of residence.