The aim of this thesis is to explore how sexual homicide offenders (SHOs) of children in the United Kingdom (UK) operate, in order to provide empirically-supported evidence that can be utilised as part of future behavioural investigative advice in relevant police investigations. Data pertaining to all relevant sexual homicides of children aged 17 and under that occurred in the UK has been provided by the Serious Crime Analysis Section (SCAS) at the UK’s National Crime Agency (NCA). This includes 81 cases; 61 solved and 20 that have remained unsolved, as of March 2023. Results show that SHOs of children in the UK have similar characteristics to SHOs in other Western cultures, with regards to age, gender and ethnicity, as do the victims in this sample. The causes of death concur with previous findings; the majority of victims are killed by a form of asphyxiation. Crime scene behaviours also indicate similarities with the Sadistic/Angry typology of SHOs (Beauregard & Proulx, 2002), but with further nuances apparent. Comparisons between the solved and unsolved cases show some differences between levels of premeditation, as pertains to the use of weapons. With regards to previous convictions of these offenders, there is a proportion that have not been previously convicted of any offences, and a small number of previous sexual convictions. When analysed alongside crime scene behaviours, varied previous convictions are linked to specific sexual assault behaviours exhibited. SHOs of children in the UK mostly travel short distances from their residences and between multiple crime locations, suggesting they are more likely to be ‘Marauder’ offenders (Canter & Larkin, 1993) and utilise mobility within the commission of the sexual homicide. Limitations of the reporting process and data, alongside recommendations for future research in this area are discussed.