Interview: Empathy for the devil: Brian Masters: He is tidy, dapper, bookish and has made friends with a serial killer. Charles Nevin on a biographer with murder on his mind

ONE FIGURE stood out in last week's litigated and unconvincing television documentary about serial killers and how to catch them. This was not Dennis Nilsen calmly discussing bodies and how to dispose of them, nor any of the other murderers and victims spliced in to pep up the talking policemen. It was Brian Masters, walking through an Oxford quadrangle in his pink and green Garrick Club tie, lending a note of Establishment respectability to the otherwise sleazy proceedings.

Masters, Nilsen's biographer and continuing confidant, presents a problem for the easy and current condemnation of the world of True Crime, with its breathy reconstructions of every wound and horror. Masters lacks the crassness and the general prurience of the genre. His latest book is about Jeffrey Dahmer, the Milwaukee decapitator, necrophiliac and cannibal; his previous one was a biography of E F Benson - creator of the gentle Mapp and Lucia satires. Masters gives pause.

Killing for Company, his book on Nilsen, is a careful study of the killer's life, interspersed with lengthy comment from the clankingly articulate and endlessly contradictory Nilsen. Masters approached him after his arrest and found an eager, obsessively self-analytical collaborator, remorseful and remorseless in rapid turn. The book contains Nilsen's poems and his drawings of some of his 15 victims, naked and dead.

There is much speculation from Masters about cause and motive, nods to Sartre and Swinburne, Dostoevsky and Freud, an examination of necrophilia, and no particular conclusion. But it is the murders themselves - the treatment and disposal of the young men's bodies, the head boiling in the saucepan - that grip and appall.

Masters repeats his technique in The Shrine of Jeffrey Dahmer, to be published next month by Hodder & Stoughton. While there are obvious similarities between the two necrophiliac homosexual murderers who killed to keep people, Dahmer's 17 murders, if such things can be rated, are worse: his attempt, for example, to drill a drugged victim's brain to create a sex zombie. But the book is not as impressive as Killing for Company; Masters did not have access to Dahmer, only to his interviews with a psychiatrist; there is less of the feel of exploration by a shocked but inquisitive outsider.

There are signs, too, that it is being greeted with less respect than Killing for Company. In the Modern Review, Martin Cropper has called Masters a 'gore bore', a PR for maniacs. In the Guardian, psychiatrists and psychologists have questioned the point of these books, well-written or not. There are worries that the wrong people read them for the wrong reasons. Robert Bluglass, Professor of Forensic Psychiatry at the University of Birmingham, says they don't help us to understand, only 'feed a morbid public curiosity'.

BRIAN MASTERS is as reassuring at home in West London as he was in the Oxford quad. No Garrick Club tie, but a suit none the less. No black wallpaper and incense, either. 'I don't think the public interest is morbid,' he says. 'Does he (Bluglass) think we all like to imagine cutting people up? But we're all interested in aberrant behaviour, aren't we? It's perfectly natural to be interested in extremes, in extravagances, in peculiarities . . . extraordinary murders are worth looking at because they open a window on the human condition in a way that someone who batters his wife to death because he is fed up with her does not . . .'

He accepts the deficiencies of much of the genre - and last week's documentary - but argues that 'knowledge is always preferable to ignorance'.

'The contemplation of extraordinary human behaviour with vile effects reminds one of the fragility of human sanity . . . and I think studying these terrible crimes makes one more grateful for life as it is, and increases one's potential for pity, by which I mean one doesn't pity the murderer more than his victim: one pities all mankind . . .

'It's not just putting a microphone in front of his face and saying, 'Tell us, Jeff, how do you do it?', that would be inexcusable . . . at no point do I say it wasn't really his fault, and, ahhh, poor boy, he was driven to it . . .'

Nevertheless, his American publishers did feel, initially, that his treatment of Dahmer was too sympathetic; and that is the burden of Cropper's attack in the Modern Review on both Killing for Company and the Dahmer book. 'People think in simple terms,' says Masters. 'Sympathy is the obvious word which occurs to them, but it isn't sympathy, it's recognition of something deeper, more subtle and more complicated than what appears on the surface, horrendous as that may be.'

Masters acknowledges the distress that his books might cause the relatives of the victims whose sufferings are so compellingly described; he argues that this must be balanced against the need for an honest attempt to understand. He produces a letter from Rampton Hospital, thanking him for a lecture and saying that he had provided more insight than many a professional. Killing for Company, he tells me, is required reading on many university psychiatry courses. And Masters has his professional supporters, such as Anthony Storr, an Oxford psychiatrist, and John Gunn, Professor of Forensic Psychiatry at the Institute of Psychiatry, who thinks some of the opposition is caused by antipathy to a talented amateur on the patch.

But why should someone like Masters want to write about such things? After all, before Killing for Company he had written studies and biographies on French literature and British royalty and aristocracy.

Well, he says, all subjects of biography are at the extreme, or they wouldn't be worth writing about. He read of the Nilsen arrest and saw a picture of the murderer with what looked like a copy of the complete works of Shakespeare under his arm. 'I remember thinking, 'I bet there's more to this than meets the eye.' I'd never done a criminal case and I wondered if I could . . . I treated it just as I treated the Duchess of Devonshire, as just another job of work . . . it wasn't as if it changed my life and I've been obsessed with it ever since.' The Dahmer book, he says, will be his last on murder.

Masters was born in South London in 1939. His father worked in an aircraft factory, then in a hotel laundry, then buying and selling chickens in Wales. Masters went to a grammar school in Camberwell, then to University College, Cardiff, and Montpellier University. After university he taught languages and did guided tours. He taught French to the Marquess of Londonderry's daughters and wrote a book about the family. (He has also written a biography of another friend, John Aspinall.) The Garrick, he says, is where he feels most at home.

There is no doubt of the extraordinary empathy that he contrives with Nilsen and Dahmer. Ask him if that is because he has also been an outsider, and he says he has never thought about it. Ask him about his sexuality, and he says that 'the writer's own sexuality is hugely irrelevant. You can write about Florence Nightingale without being a 19th-century spinster'.

THE relationship with Nilsen remains an odd one. Is he a friend? 'I don't know what to call him. I suppose he's a subject . . . no, I'm not afraid of it, I suppose he is a friend in a peculiar way. After 10 years of visiting he is someone I know quite well.' But he says Nilsen can be arrogant and tedious, and that 'it's almost certain I wouldn't have liked him if I'd met him on the outside . . . I would find it very difficult to face myself if I had just said 'Thanks for all your help, the book I wrote has won a prize (the Gold Dagger), now goodbye and you can rot.' I will go as long as wants me to.'

Lord Longford also visits Nilsen; Longford thinks he is redeemable, Masters does not. 'He is being duly punished by society for what he did, which he knows perfectly well was wrong.' But he thinks it wrong that Nilsen receives no psychiatric help: he may be legally sane but he is 'mad in his soul. He can make a cup of coffee and eat a slice of toast with the head of somebody bubbling a few inches away. If madness is anything, that is it'.

Martin Cropper, in his review, called Masters the keeper of Nilsen's boiling pot. Masters laughs at this. 'There's a germ of truth in it . . . Nilsen said, 'Look, I'm in prison for the rest of my life, you might as well be my heir'. So he instructed the police to give me his belongings which included his clothes, a few pots and pans, knives, forks and plates, the television set, a radio-cassette thing . . . but they did not include the cooking pot.

'I kept his things here for a little while, but I've given them to Madame Tussaud's. Except, curiously, I kept the radio-cassette thing, because I did wonder if objects could bring evil with them in their train . . . Three people who were listening to music on that thing died, they were throttled, but do you know, it's so innocuous I can't even remember which room it's in.'

Nilsen and Dahmer have both given opinions on the interest in them. Nilsen: 'I am always surprised . . . that anyone can be attracted by the macabre . . . Their fascination with types . . . like myself plagues them with the mystery of why and how a living person can actually do things which may be only those dark images and acts secretly within them.' Dahmer: 'It's just a sick, pathetic, wretched, miserable life story, that's all it is. How it can help anyone, I've no idea.'

Masters will visit Nilsen in prison tomorrow. His next book is on saints.

(Photograph omitted)