This paper describes a research method used to develop criminal personas for use by designers in a process called Cyclic Countering of Competitive Creativity (C4). Personas rather than profiles are developed to encourage designer ownership, to improve the level of engagement with countering the criminal mind, and encourage the responsibility to keep the personas live and developing, rather than be adopted as simple checklists built from available criminal profile data. In this case study indirect access to offender details was used to develop the personas. The aim was to give particular focus to the offenders’ ‘creative prompts’, which enable designers to more effectively counter their own design solutions, by a role-play approach to critical review and counter design. The C4 process enables learning through failure, and strengthens the development and selection that takes place within the design process, but C4 does rely upon the development of relevant and engaging personas to be effective.