We are working with local law enforcement to understand the potential for extended reality technologies to enhance crime scene investigation. Police have used 3D reconstruction of crime scenes for some time to investigate and communicate complex details with courts and juries. However, the cost and complexity of 3D capture and modelling software means that such reconstruction is only done by expert teams in high-profile cases. We are currently prototyping easy-to-use tools intended to allow police, who are not experts in 3D modelling, to quickly create digital twins of crime scenes directly in an immersive environment. In this paper, we report on our early discussions with police digital CSI experts, our survey of the state-of-the-art which identifies certain gaps, our early results, and our vision for future CSI tools.