Meet Jonathan Aris who plays DCI Mark Glover in new BBC drama The Sixth Commandment

What sort of a character do you play?

DCI Mark Glover is brilliant and has an amazing mind. He’s an incredibly dogged investigator and very impressive, really. He’s also softly spoken and underplays his status, motivating his team by quiet encouragement and suggestion rather than throwing his weight around. He has a great team and, like him, they all seem to be determined and relentless, doing everything for the right reasons for the families of the victims and for the truth, not - as far as one can tell - for personal glory.

How did you go about researching the role?

Before filming began, I learned a good deal from watching the Catching a Killer documentary and did as much research as I could around that. The investigative team come across as deeply impressive and it's not a side of police work that you often see dramatised in this way. Usually police teams are, you know, riven by conflict or struggling with tragic personal flaws or whatever, whilst this is just an example of brilliant, intelligent policing - and they won't quit until they've got their man.

What was your reaction to Sarah Phelps’ scripts?

My character arrives in episode three, obviously after the victims have suffered their fates and the investigation kicks off. I thought the scripts were exceptional, very moving in their portrayal of the victims and the surviving family members, very impressive in depicting the way the investigation unfolds, and the way in which the police and the legal system have to wrestle with an unbelievable mass of information, great complicated timelines and all sorts of source materials. The scripts are also structurally really interesting, because each one is like a separate chapter, a little chamber piece unto itself. Combined they tell this shocking and extraordinary criminal story. What Sarah Phelps has done so brilliantly is to ensure your emotional investment with almost every character. So as much as you're horrified and repelled by Ben Field, you're also fascinated and drawn in just as the poor victims are. It's an absolutely heart-breaking story, brought to life by brilliant actors.

Tell us more about the police investigation.

I was absolutely fascinated by the way in which the police had to turn this morass of information into a simple, clear legal story that a jury could understand in the hopes of bringing Ben Field to justice. The police got drawn into the case two years after Peter had died apparently of natural causes. So it's all retrospective, speculating about what might have happened, but in the absence of much forensic, concrete evidence, which is really hard for the police. There’s no longer a crime scene. They have to go back and go through Peter’s extensive journals, so it's a deep dive into research material as much as anything else. Mark and his team are doing extraordinary things that other people can't really understand.

The job must be very demanding?

It is - not only are they banging their heads against paperwork most of the time, but they’re also going out to some very difficult autopsies, or giving unsettling news to victims’ families. Those would be very difficult meetings to hold in real life but no matter how hard or painful it might be, you just have to keep going until the job's done.

Did you feel a big responsibility to be accurate and respectful?

I've met the real Mark Glover who visited the set and I found that tremendously useful and interesting, but also reassuring that he was on board. He seemed to be very interested in how a film unit works and he thought the level of realism, the sets and the art direction were impressive, so that was great. But you’re very conscious you don’t want to upset the people still alive, let alone the relatives or the memory of the deceased. I’ve been working with such fantastic actors who give such sensitive truthful performances and there's an aura of respect around the whole project, I think,

How did you find working with Éanna?

Working with Éanna elicited all sorts of simultaneous feelings. Firstly, in the presence of a remarkable performance - I've worked with him before on something quite different so to see him undergo this transformation is very impressive. Also, because we'd all studied the documentary so closely, we're very aware of what Ben Field himself looks and sounds like and of how he behaves. Therefore when you see this recreation in front of you in the flesh, it's startling and very, very creepy. I can't remember having been quite so chilled in any other work I've done. It really was an extraordinary experience.

What do you think is the appeal of this particular story?

What's unusual about this series is that the crimes themselves are so extraordinary and Ben Field’s character so bizarre and ghastly that they almost defy dramatisation - if it wasn’t true, you wouldn't believe it. That takes you as a viewer to some quite unsettling places but it plays out in this very understandable human, delicate way.