This episode uncovers the forensic imaging expertise behind the eventual capture of Michael Hardacre, the 'Rochdale ripper'.

In the summer of 2000, a series of attacks in Rochdale left the community terrified. Police began a major investigation but had little to go on. They weren't even sure if the crimes were linked. But advances in forensic imaging meant one expert witness was able to help by revealing evidence that put the attacker behind bars.

The programme also explores how translating slang exchanges between friends on an online chat revealed a chilling murder plot. Digital messages, texts and emails are a vital source of evidence for detectives. But with modern slang always changing, understanding these messages can be a challenge. It’s not just a question of who said what to whom; detectives also have to prove what that person actually meant. That's when it’s time to call in an expert witness known as a forensic linguist. Show less