Robbie Coltrane's Critical Evidence

In 2002, an off-duty fireman discovered a body in a field charred beyond all recognition. All the police knew was that the man had died a brutal death, having been stabbed repeatedly, shot in the head, and drenched in petrol before being set alight.

When a Devonshire fisherman hauled in his nets on July 28 1996, he made a gruesome discovery: among that day's catch was a dead body. There was nothing to identify the man's body except a Rolex watch and a small maple leaf tattoo on his hand.

In 1984 a parcel bomb was sent to a 53-year-old grandmother living in a tranquil English village. She died of horrific injuries. No one understood why it had happened. The only evidence detectives had was the bomb itself.

Hilda Murrell, a 78-year-old distinguished rose-grower, was found dead in woodland near her home town. Despite a huge investigation by the British police, detectives failed to find her killer and conspiracy theories muddied the waters still further.

On 12th May 2014 a human torso was discovered in a suitcase during routine maintenance work on a Birmingham canal. With no useable DNA and no other body parts, the case initially seemed impossible to crack.

In November 1993, Derek and Eileen Severs disappeared without a word. When police spoke to their son, Roger, he insisted they were on holiday. However, there was no evidence of this apparent trip, and Roger was soon arrested on suspicion of murder.

In the summer of 1993 a serial killer stalked London. The Metropolitan Police investigated a bizarre murder in which a man was found naked on his bed with a dead cat draped over him. He'd been strangled and his flat had been wiped of evidence.