I, Sniper: Should conversations with a real-life serial killer take centre stage on screen?

Marion Lewis at his daughter's gravesite in Mountain Home, Idaho. Lori Ann Lewis-Rivera was vacuuming her minivan when she was shot dead by Muhammad and Malvo in 2002. Photo / AP

During the many years spent making her new documentary about the Washington DC sniper attacks, Mary-Jane Mitchell's children got used to Mummy taking urgent work calls. The phone could ring day or night, sometimes when she was reading Harry Potter at bedtime, at which point she would hurry off into another room.

Yet the calls weren't from some demanding Hollywood big shot, or one of the snipers' traumatised victims, many of whom feature in the six-part series. They were from a Supermax jail in Virginia, and on the line – never for more than the jail's 15-minute limit – was the surviving sniper himself, Lee Malvo, currently serving six consecutive life sentences without parole. During Malvo's killing sprees, 17 people were killed.

In what is perhaps the ultimate in confessional television, Malvo's recorded phone interviews are centre-stage in Mitchell's documentary, I, Sniper: The Washington Killers – narrating both his troubled life and the three-week shooting spree that spread terror through Washington DC in October 2002.

So what was it like being at "the beck and call of a serial killer", as Mitchell puts it? "Often the calls would come at night, and I had to barricade the children screaming and crying in their bedrooms to take his call, which was always very hard," she tells me from New York. "He'd also ring at Christmas and Thanksgiving because that was when prisoners get more chances to make calls, or when or I was driving or at the cinema."

John Lee Malvo, then aged 17, is escorted from court after his preliminary hearing in Fairfax, Virginia on January 14, 2003. Photo / AP

Now 36, Malvo is one of America's most notorious serial killers – a title for which there are, sadly, no shortage of contenders.

He and an accomplice roamed America's capital in a Chevy Caprice fitted with a gun peephole hidden in the boot, shooting dead 10 random people and wounding three more. With America still reeling from 9/11 the year before, the attacks sparked panic that an Al-Qaeda lone wolf or white supremacist was loose.

Instead, those eventually arrested were Malvo, then just 17, and John Allen Muhammed, then 41, a Gulf War veteran and Nation of Islam member, who claimed the shootings were part of his own private war on white America.

Like most terrorist atrocities, the reality fell short of the rhetoric. Muhammad was angry not just with whites but society in general, after losing his children in a custody battle.

And when the shooting began, the targets were anyone who strayed into the crosshairs of the duo's AR15 assault rifle: black, white, old, young. Among them was Iran Brown, a 13-year-old boy, who only just survived a bullet to the abdomen. At the scene of Brown's shooting, police found a Tarot Death card, inscribed "Call me God".

John Allen Muhammad at his sentencing on October 3, 2007. Muhammed was executed by lethal injection on November 10, 2009. Photo / AP

As Malvo admits in the interviews, he was at the time "a monster". He was also, though, a very disturbed teenager, who was abandoned by his father, beaten by his mother, and left homeless by 15. In one final stroke of bad luck, he then chanced to meet Muhammad.

The older man, it seems, became first a surrogate father, then a psychotic Fagin – teaching Malvo how to shoot at a gun range, sexually abusing him, and grooming him into his own terrorist enterprise.

In the months before the DC attacks, Muhammad took Malvo on a "training mission", an inter-state road trip in which they killed seven people in robberies. Malvo says Muhammad told him: "To do what we need to do, you have to become what I need you to be. And in order to do that, what you were has to die."

Muhammad was executed by lethal injection in 2009 – a fate Malvo was spared because of his youth, and amid pleas from his defence team that he'd been led astray. He has since apologised to his victims, and says that two decades in prison has offered plenty of time to repent. Yet is it right for him to be such a central voice in a documentary about his own crimes? Could it give him undue celebrity?

Documentary film-maker Mary-Jane Mitchell. Photo / Supplied

In fairness, British-born Mitchell, 48, does not come across as a lurid purveyor of tabloid TV. An LSE-educated criminology graduate, she has followed Malvo's case since 2002, when she was working as a Channel 4 documentary maker, and persuaded them to send her to cover the shootings. "It was terrifying, the only time I've ever worn a ballistics jacket while filming," she says.

She began corresponding with Malvo in 2006, still intrigued by his story, but says it was not until the advent of streaming services, and the popularity of complex, long-form true crime series such as Netflix's Making a Murderer, that a documentary seemed feasible. She also says that as Malvo is unlikely to ever get parole, he has little incentive to lie.

"The film is an examination, not an exoneration, and a chance for him to offer his victims an answer to why this happened. But you don't get to the end of the film and think 'he shouldn't be in prison'," she says.

The documentary also features survivors and the bereaved, who spell out how horrific the attacks were. Restaurateur Paul LaRuffa was shot six times by Malvo during one of his "training" robberies. LaRuffa suffered months of trauma afterwards, convinced that anyone using that level of savagery must have borne some personal grudge, and might return.

Marion Lewis holds up a photo of his daughter Lori, her husband Nelson Rivera and their daughter Joselin. Photo / AP

"I had flashbacks whenever I tried to sleep, which only eased once the two were arrested," LaRuffa says. "Back then I hated Malvo, but I do think he's a different person now. A few of my family think the film is a little too centred around Malvo, but you do get to hear what was in his mind, and I think it's pretty amazing they've done it like that."

Also interviewed is Isa Nichols, a businesswoman who helped Muhammad's ex-wife, Mildred, in her custody battle for the couple's children. In revenge, Muhammad sent Malvo to Nichols' house to kill her. When Nichols' niece Keenya, 21, answered the door, Malvo shot her instead.

Nichols attended Muhammad's execution – so many bereaved families were present, she says, that there was standing room only. "Some were asking if they could press the [injection] switch, one man said he wanted popcorn and beer," she recalls. "They'd lost loved ones, so who's going to tell them how to feel? For me, though, it just felt just like more death and pain."

One positive that could be salvaged from all the horror, Nichols says, would be for America to end sentences of life without parole for juveniles – especially neglected youngsters who have fallen "under the influence of predators".

While Malvo himself has limited hope of ever leaving jail because of the scale of his crimes, there are many lesser offenders, she argues, who could and should.

Lee Malvo is serving six consecutive life sentences without parole. Photo / Virginia Department of Corrections via AP

Meanwhile, back at her home in New York, Mitchell has taught her own children about the mysterious caller who used to interrupt bedtime stories. "I had to figure out how to integrate Malvo's constant presence in our lives, and in the end I decided to teach them about who Malvo was, and what he had done, and why I was speaking to him," she says.

Mitchell ended up framing what had happened through the character of Voldemort, Harry Potter's nemesis, as a way of showing her children how monsters are made (coincidentally Malvo is also a fan of Harry Potter). "Likewise Voldemort is a lonely child who ends up angry and killing people. [This] helped the children understand that we all have more in us than the worst thing we've ever done."

• I, Sniper: The Washington Killers is available to view at DocPlay.com