Expert Witness - Season 4

When eight-year-old Sarah Payne is murdered, a pollen expert finds a vital link between the suspect and the grave. In another case, a blood spatter expert is called when a body is found in a freezer.

A twisted killer throws two suitcases containing severed remains into a canal, and it's down to a 3D-scanning expert to uncover the crucial evidence needed to convict him.

When a body is found in a wheelie bin in a lake, a cell site analyst tracks the suspects' mobile phones. And when a man disappears, a soil expert helps identify his killers.

When a killer gang use a secret language to discuss an attack, police turn to a forensic linguist. And a huge cannabis operation is brought down with the help of a drugs expert.

Untying the knot of a dressing gown cord used to kill a woman 35 years ago finally reveals her killer. And expert analysis of muddy shoes helps find the murderer of a missing student.

In a case of mistaken identity, a man is stabbed to death. An intelligence analyst helps convict the killers, and a trace evidence expert helps find the weapon used to kill a teenager.

Thirty years after six-year-old Rikki Neave was murdered, a soil expert helps convict his killer. And a wildlife forensic scientist helps police in an illegal ivory investigation.

After fire crew find a body in a burning flat, a blood spatter analyst uses an untested method to find key evidence. And a cold case is solved using familial DNA for the first time.

A teenager is found dead in the woods. A pathologist analyses her stab wounds to shed light on the attack, and when remains are found in Scotland, a crack team of experts nail the killer.

The fatal shooting of Olivia Pratt-Korbel in Liverpool. An image analyst helps detectives unmask the killer. And two experts help police convict thieves who stole ancient treasure.

A mother and her son vanish in 1976, leaving just a burnt-out car. Forty years later, a blood analyst helps police find out the truth. And a phone analyst helps find the killer of a drowned man.

Rachel Nickell was murdered in 1992. Ten years later, a team using new DNA technology finally identify her killer. In another case, a trace expert uses beer glass fragments to find an assailant.

A young boy is murdered, but his killer is not found. Thirty years on, a pollen expert finds crucial evidence. And a blood and fibre analyst helps find the killer of a shopworker.

A disabled woman is murdered and her neighbour is the prime suspect, but it takes a doctor to help put him in jail. And a linguistics expert helps convict a man stalking his ex.

The 2005 murder of a Glasgow woman goes cold, but 17 years on, a Dutch soil expert helps convict the killer. And in another murder case, a blood analyst uses an unusual technique to crack the crime.