Some criminal investigations are so complicated that they require a number of expert witnesses to be involved. This programme examines how forensic evidence from a whole team of scientists turned a missing-person case into a hunt for a murderer, and then into an investigation into one of Britain's most notorious serial killers.After the body of a young Polish woman was discovered in the basement of a church in Glasgow, police observed an element of organisation and methodology behind the killing and became convinced the culprit had murdered before. They launched a huge operation to dig into the killer's life: where he had been living, what he had been doing, and which nearby crimes remained unsolved? Their investigation led them to two cold cases, but only evidence from expert witnesses could reveal if these were the work of the same killer. The police enlisted the help of forensic scientists Jennifer Miller, Carol Rodgers and Peter Faulding - experts in a range of different disciplines, from bioarchaeology to forensic biology and ground-penetrating radar testing - to help them gather evidence. And despite the passage of time, the experts ensured that no piece of evidence was overlooked and that the truth was finally discovered.