Stained bank notes hold the key to tracking down a brazen bank robber, and hidden-camera footage from a hi-tech sting operation helps snare a prolific gang of thieves.

A travel card holds the key to convicting a violent offender after a spate of random stabbings. Police taser the man whilst he brandishes weapons on a public street. Also, a bureau de change receipt helps put a pair of thieves behind bars after they subject their victim to a terrifying ordeal.