Expert Witness

Some criminal investigations are so complicated that they require a number of expert witnesses to be involved. This programme examines how forensic evidence from a whole team of scientists turned a missing-person case into a hunt for a murderer, and then into an investigation into one of Britain's most notorious serial killers.

After the body of a young Polish woman was discovered in the basement of a church in Glasgow, police observed an element of organisation and methodology behind the killing and became convinced the culprit had murdered before. They launched a huge operation to dig into the killer's life: where he had been living, what he had been doing, and which nearby crimes remained unsolved? Their investigation led them to two cold cases, but only evidence from expert witnesses could reveal if these were the work of the same killer. The police enlisted the help of forensic scientists Jennifer Miller, Carol Rodgers and Peter Faulding - experts in a range of different disciplines, from bioarchaeology to forensic biology and ground-penetrating radar testing - to help them gather evidence. And despite the passage of time, the experts ensured that no piece of evidence was overlooked and that the truth was finally discovered.

A young schoolboy is mysteriously shot in the head while playing in the school yard, but who fired the gun and from where? Philip Boyce, a forensic ballistics expert, is called in to test-fire a number of different guns and reconstruct the injuries to find out who fired the gun.

A successful murder investigation isn't always just about finding out who committed the crime. Police and prosecutors often have to prove the how and the why. When the body of a woman is found in a river in Wiltshire, the police turn to an expert in an unusual forensic discipline to help solve the crime. Paul Bagnall's expertise in forensic handwriting identification helps prove intent and premeditation and decode the killer's motives.

Following the unexplained death of a man in Yorkshire, found alone in his home with no signs of forced entry or a struggle, police were at a loss to explain his death. They turned to expert witness Duncan Campbell to help solve the mystery. Duncan, a forensic scientist, decided to analyse something that is part of everyday life, food. After examining the man's final meal, the expert witness not only solved the crime, but in turn helped to make legal history by ensuring a guilty verdict was achieved in this very rare and unusual case.

Sometimes, before a murderer can be identified, the victim must be identified. Such a challenge faced the police when human remains washed up on a beach in Scotland. Detectives enlisted the help of expert witness Caroline Wilkinson to identify the body of the unknown victim. An expert in forensic facial reconstruction, Caroline was able to rebuild the facial features of the young woman. This allowed police to identify the victim and in turn enabled them to catch her killers and put them behind bars.

After a 25-year-old woman goes missing in Bristol, the police launch a major missing-person enquiry. Soon after, the body of the young woman is discoved by dog walkers on Christmas Day, and the hunt becomes a major murder enquiry. As investigators can find no sign of forced entry to her flat, they conclude that her killer must be someone known to her.

The investigating officers initially hope DNA evidence would lead them to her killer, but when this evidence fails to reveal any further leads, they turn to Kelly Sheridan, an expert in fibre analysis. Her first priority is to see if there are any foreign fibres on the victim's clothes. The evidence she finds proves crucial in identifying and convicting the killer, who is not who the police thought.

In Wales, we discover how the analysis of mobile phone data helped convict the men behind a brutal murder. Initially, the police thought they were investigating a violent burglary, but following the death of a young man, their investigation immediately turned into a murder inquiry. Expert witness Paul Hope then found texts on a phone that put friends of the victim in the frame.

This episode follows two shocking criminal cases in Yorkshire, each involving a woman murdered by her partner and two expert witness with very different disciplines in forensic science who help to deliver justice.

We often think about crime scene investigations as being about the DNA left behind in traces of blood, hair or skin cells at the site of an attack, but in our first story, it was the site itself, the natural environment, that provided the biggest clue to detectives. A young woman went missing in Hull, and despite an emotional appeal by her partner, he soon became a chief suspect in the missing woman's case. But suspecting who might be the perpetrator of a crime is one thing; proving beyond reasonable doubt that the suspect was responsible is another. Police asked for help from Patricia Wiltshire, a forensic ecologist. The partner of the missing woman initially claimed he had killed her by mistake but couldn't remember where he had buried her body. Patricia was given access to his car and footwear, and was able to use her botany skills to pinpoint where the body of the missing woman was and help prove it was murder.

And in Melsonby, analysis of blood spatter found at a crime scene revealed the truth behind a husband's lies. A woman was found dead in the home she shared with her husband, above a post office. Her husband claimed that she had been held hostage, but this didn't fit the timeframe. The police asked Jo Millington, an expert in blood spatter analysis, for help. Jo showed that the direction of blood at the crime scene meant there may never have been a break in, and the husband was convicted of murder.

In our first story, a community reels in total shock when a doting grandmother is found murdered in her home. Detectives search for the killer and suspect it may be someone close to her. The suspect's DNA is found all over the crime scene, but that is easily explained because he lived until recently in the same house. So the police try another route. They approach Kelly Sheridan, an expert witness in fibre evidence, who uncovers a trail of fibres, unravelling the mystery and putting the killer in jail.

More than 40 years ago, fibre analysis was still a relatively new forensic discipline. Despite this, police hoped it could help solve a string of child murders in the 1980s and 90s, but in the end it took old-fashioned detective work to close the case of killer Robert Black. Looking back, the case shows how this area of forensic science has been transformed over just four decades. Jim Fraser was the lead scientist in the Black investigation, and his experience shows that scientific progress is achieved through failure as well as success.

An expert witness uses soil analysis to find the body of a missing woman feared murdered, and a cell site expert uses his tracking skills to catch a killer in Northern Ireland.

When a young nurse disappears, a soil analyst helps find her body and solve the crime. A digital imaging expert proves that what was thought to be an accidental death was murder.

An expert in microscopic lifeforms helps solve the murder of a teenager, and a handwriting expert assists an old lady whose house has been sold without consent.

A blood spatter analyst unlocks the mystery of a woman murdered in her own car, and an expert witness uses a mobile phone to help detectives solve a baffling murder case.

Police turn to a footprint analyst and a pollen expert to help solve a murder in Manchester, and a soil expert unearths the evidence needed to arrest a gang of treasure thieves.

Blood spatter analysis helps identify the killer of a body found in a suitcase, and an expert helps in a serious case of financial fraud that cost some victims their life savings.

An expert in mobile phone technology tracks the movements of a murder suspect, and an expert in art fraud determines whether a very expensive painting is genuine or fake.

A dental expert helps police investigating the mysterious death of a teenage girl, and an autograph expert is brought in to help convict scammers selling fake celebrity signatures.

When a man kills four people and goes on the run, a handwriting analyst is brought in, and after a body is found, an expert in pollen links the suspects to the scene of the crime.