The first episode looks at the difficulty of identifying the body in a murder case. The question of identity is a crucial start to the investigation. From charred bones to bodies completely dissolved in acid, with each horrific new case science has had to adapt to identify both the victim and the murderer. Investigating four breakthrough cases, Gabriel reveals the scientific innovations that tipped the scales of justice in favour of the detective - and caught the killers.

There will always be those who think they can commit the perfect murder. In reality it's virtually impossible to leave no evidence at the scene of a crime. Fingerprints, hair, fibres and blood can all lead to the killer. In this second episode, Gabriel explores the cases that were solved by examining the smallest traces of forensic evidence, from the first murder case solved in the UK based on fingerprint evidence to the patterns of blood in a bedroom which helped overturn an infamous murder conviction.

Where there's a murder there's usually a weapon. It's a key piece of evidence that can hold all the clues needed to catch the killer and shine a light into the mind of the murderer. In this final episode, Gabriel investigates the forensic advances that have elevated the murder weapon from its role of mere evidence to that of key witness.