From the UK's leading forensic scientist and Sunday Times bestselling author of All That Remains and Written in Bone: a gripping exploration of forensic science, told through often shocking real cases to assess its triumphs, failures, and future. 'No scientist communicates better.' Val McDermid, award-winning author of the Detective Karen Pirie series For over forty years, Professor Dame Sue Black has analysed criminal evidence at the highest level. As the UK's leading forensic scientist, she has stood in court as an expert witness, repeatedly putting her research and reputation on the line, all in the name of justice. Now in An Expert Witness she puts forensic science itself on trial. Drawing on shocking real cases and true crime, from historic poisonings to modern sexual offences, Sue Black traces the evolution of forensic science, from early identification methods to more recent breakthroughs such as DNA profiling, Sue's own vein identification research, and the emerging role of artificial intelligence in criminal investigation. She shows where science has delivered justice, and where failures have led to devastating consequences, including wrongful convictions such as that of Andrew Malkinson, imprisoned for seventeen years for a crime he did not commit. As she reflects on life serving as an expert witness, Sue looks back at landmark cases to tell the story of forensic science, ask questions for its future, and explain why this book marks the close of a defining chapter in one of the most extraordinary careers in modern forensic science.