Robbie Coltrane's Critical Evidence

The police arrive to discover a man's body has been charred beyond recognition. All they knew is that his killer or killers having stabbed him repeatedly, shot him in the head and drenched his body with petrol before setting it alight.

Robbie Coltrane examines the case of Canadian banker Albert Walker, who murdered and assumed the identity of his business partner in England.

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, and the only evidence detectives had was the bomb itself.

A 29-year-old hairdresser was found brutally stabbed on her doorstep in a quiet suburban street of London. A recording of a threatening phone call seemed to suggest the motive, but every lead comes to a dead end.

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 May 12th 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.

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.