Key to understanding the significance of behavioural evidence for linkage purposes is in establishing how consistently an offender displays the same or similar behaviours across their series. There have however to date been very few studies aiming at identifying salient components of offending behaviour that can be used reliably for linking individual crimes as part of a single series. In addition, studies that have been conducted have all dealt with serial homicide in the Western world and have been based on small samples of cases from each country. Some of the recent literature has started to disentangle some of these salient features, notably the victim, violence levels, control, and planning. The current study focused on evaluating the consistency of these features across series, using a sample of serial homicides from South Africa consisting of 30 offenders with a total of 283 victims and 235 crime scenes. Results indicate that the level of interaction with the victim may be influential to the stability or instability of offending patterns across the series. How offenders approach planning in their offence also showed a certain degree of consistency, with patterns of violence being the least consistent across the series of all components tested. Copyright © 2014 John Wiley & Sons, Ltd.