I Interviewed the Forensic Pathologist Who Worked On Harold Shipman's Body

As I'm led underground through the labyrinthine corridors of a mortuary in the North of England, I come to a room with a large internal window that looks into another, dimly-lit and murky-looking space. It's filled with coffin-sized metal containers, which house all manner of sterilisers and medical equipment. The smell of sanitiser hangs in the air like the breath of a drunk.

In the middle of the room is a shiny, stainless steel table where hundreds of dead bodies – including mass murderer Harold Shipman – have been dissected, examined, and probed. "I knew who it was, but I just treated him as I would any other individual," says forensic pathologist Dr Philip Lumb, a small, slight 43-year-old man with a delicate northern lilt. "He was treated with respect, with the neutrality that I afford to everybody. He was just another guy."

Lumb carries out post-mortems on up to nine bodies a week, many of which are murders. Describing how bodies are "shredded" if they're hit by trains, the dryness in his tone is as if he was describing the decor in his home hallway – which is precisely what you'd expect from someone dealing with death and all its viscera day in, day out. Gallows humour, you imagine, is a prerequisite for his job.

An important part of a forensic pathologist's job is to give evidence in murder trials. When a suspicious death occurs, the pathologist is an integral part of the investigation. Police will call a pathologist to the scene to examine the body of the deceased and look for clues pertaining to the cause of death. The pathologist will then later carry out a post-mortem on the body and write a report that determines the cause of death. If the pathologist suspects a murder, they will often be called to court.

Silent Witness was the first show that really brought the world of forensic pathology into popular culture, but every crime show in the world now touches upon it in some way. The Wire, Dexter, CSI, The Fall – all use bit-part actors to illustrate how important thorough post-death examination is making cases. But Lumb can barely watch them without "tearing his hair out", as the reality of waiting for DNA and toxicology results is much more frustrating than TV shows let on. He explains that it can take weeks for results to come back from the lab and emphasises the importance of these results being interpreted correctly. "If you make a mistake, somebody could go to prison for 20 odd years," he says.

Such is the sensitive nature of his job, Lumb has to, for the most part, be discreet about his personal life and the cases he has worked on – the risks involved with regularly standing as a witness demands a certain degree of anonymity – so is unable to reveal any details about his life outside of work – partners, family, etc. The small, bespectacled man therefore cuts quite a mysterious figure as he moves around the room. He is utterly defined by the intricacies of his work. I wonder, for a second, if Philip Lumb is even his real name.

He is, however, able to discuss several high profile cases that he's been involved in, as he is already named as the forensic who worked on the cases online. This includes the double murder of Robert and Patricia Seddon by their son, Stephen. In July 2012, Stephen Seddon, 46, murdered his parents with a sawn–off shotgun at their home in Sale, Greater Manchester. He'd tried before, by driving into a canal with them strapped in the back seats in a faked road accident, and, when he did eventually succeeded in his plan to collect his £230,000 inheritance, Seddon tried to cover his tracks by placing the gun in his father's hands.

Lumb had originally been told that he was going to the scene of a murder-suicide. However, the positioning of the weapon and the angling of the bullet holes proved that it was impossible for Robert Seddon to have shot his wife and then himself. "It's quite nice to be able to turn round to the police and say, 'I'm sorry, but you've got a murder here.'" In March 2013, Stephen Seddon was found guilty of the double murder.

While such cases provide an immense "sense of satisfaction" for Lumb, the job can also be incredibly taxing. Unpredictable hours mean that it is impossible for forensic pathologists like him to make many plans, as they are often on call. There is also no way of telling how long you will be required to stay on a scene. Lumb's longest shift lasted 24 hours. Such irregular, gruelling hours are, he says, often a bigger downside than the gruesomeness. But again, his training affords him a sense of calm, a strictly clinical approach to the cold, blue cadavers in front of him. They aren't people. They're vessels, slab of dark, dying flesh.

"I've had to deal with murders of children many times and I think everybody expects you to say that must be a lot harder, but again, our training helps us to remain neutral. Dealing with the homicide of an 18-year-old is as difficult as dealing with a two-year-old. Nobody likes to see wee babies in that position, but we have to stay neutral."

Often, though, part of the pathologist's job can involve watching videos of victims in the run up to their murder – particularly in torture cases. They have to, to confirm whether the injury is compatible with the movement of the individual on the footage. "That's disturbing, even for us," says Lumb. "It's easy to disassociate and focus on the science when the person is inanimate. However, having to watch them walking and talking on such a video can be emotionally draining." He leans back in his chair and laughs nervously. "There's still a flicker of emotion in me."

In Lumb's mind, a murder scene serves as "a snapshot of somebody at the end of their life, when it's all over". The environment that he enters surrounding the death is so controlled, so precise, that it is easy for him to detach himself from it emotionally. Forensic pathologists are generally called to the scene towards the end of the investigation. Police will secure the environment and then get biologists, blood-spatter and ballistic experts to look for trace evidence before forensic pathologists come along and start looking at the body. This allows them to get all of the fragile evidence off before the pathologist begins moving the body around, looking at the injuries and assessing how he thinks they were attained. Much of their work is done alone, says Lumb, and although they do "ask each other's opinions on cases," they are examined as individuals in court. The final determination of the cause of death lies only with the pathologist assigned to the case.

Before I leave, conversation turns to traceless murders and how it's incredibly difficult to commit them. "Though I can think of one or two ways," he deadpans. "So you'd better watch what you write."