There are two general approaches to profiling: the top-down approach and the bottom-up approach. However, in relation to the use of geographical profiling at least, there has been some successful use in a case of serial arson. A regular issue in the study of offender profiling is the question of whether the profile provided is accurate, which can be seen both from cases where it was incredibly successful like that of Canter's profile of John Duffy and Britton's unsuccessful profile of Colin Stagg. The top-down approach is one that takes a more nomothetic approach to the study of offenders and creates a typology that could be potentially applied to a number of people of a given type based on theoretical principles derived from people of a similar type. In modern times, there have been advances in all areas of police work but particularly in the use of DNA evidence.