Every contact leaves a trace, it’s the golden rule of forensic detection. A criminal will either leave behind or take with him small traces that could lead to his capture.

It’s up to the police and forensic scientists to find them. Often it’s the smallest of clues that can lead to a prosecution.

In Australia, the police followed a red haired trail in their search for a killer; in America, a kidnapper was betrayed by the wood marks on a ladder; and in Britain the distinctive fibres that caught a killer red handed.