Rachel Nickell was murdered on Wimbledon Common in South-West London on 15 July 1992. The police investigation of the crime resulted the arrest in controversial circumstances of an innocent man, who was subsequently acquitted. Many years later I was asked to review aspects of the case for the Metropolitan Police and the Crown Prosecution Service. The review led to arrest of Robert Napper, who pleaded guilty (with diminished responsibility) to Rachel’s murder in 2008.