A Death in Belmont by Sebastian Junger

As Ellen Junger returned home on 11 March 1963 the telephone was ringing. Her son's babysitter warned her to lock the doors. The "Boston Strangler" had struck again, it seemed. His ninth victim in less than a year was a Jewish woman in Belmont, the middle-class suburb where the Jungers lived.

Ellen rushed to share the dreadful news with the handyman painting the house. He had been working for the Jungers, on and off, for months and the next day posed for a commemorative photograph. In the picture the burly man stands smirking behind Ellen and her baby Sebastian, one powerful hand resting across his abdomen. His name was Albert DeSalvo and two years later he stood trial as the Boston Strangler. Frozen forever in black and white with the man convicted of l3 sexual murders, the writer Sebastian Junger has used this bizarre connection as a jumping-off point for a lucid study of crime and justice in l960s America.

Yet DeSalvo denied killing the Belmont housewife, Bessie Goldberg. Instead, Roy Smith took the rap. A black man with a criminal record, he had been cleaning Bessie's home that afternoon and was convicted on circumstantial evidence by an all-white, all-male jury. Smith always protested his innocence and Mrs Goldberg's death did bear the Strangler's signature marks. She had apparently let her murderer in voluntarily, had been raped while dying and her stockings were tied in a bow around her neck, presenting the victim like an obscene gift for whoever found her.

Did the author's mother have a narrow escape? Ellen certainly reacted quickly the one time DeSalvo, "a strange kind of burning in his eyes", tried to lure her into the basement. (She brushed him off and bolted the door.) Those other women, interrupted in writing letters, running baths, listening to Wagner, weren't so lucky. For the Jungers, Bessie Goldberg's death took on "the tidy symbolism of a folk tale".

But real life is seldom so neat. The authorities were hopelessly confounded by these murders, which happened before DNA testing was available. Even now, some think DeSalvo wasn't the man. A multiple rapist, DeSalvo hoped his confession would bring him lucrative book deals. When it didn't, he recanted. Meanwhile, Smith was pardoned after a decade in gaol but never exonerated. In 1973 DeSalvo was stabbed to death in prison. Smith died of cancer in 1976, days after he was officially freed.

A Death in Belmont doesn't solve the mystery of who did what. But Junger, whose non-fiction debut The Perfect Storm became a bestseller, has produced a compelling reexamination of the facts. He discusses classic characteristics of serial killers, traumatic dissociation, the behavioural traits of innocent and guilty suspects. He painstakingly explains everything from how "carotid takedown" works to what guilty "beyond a reasonable doubt" means in a murder trial. And Junger puts the events into context. We're in no doubt as to what life was like for black men in the still segregated Deep South, nor about the emotional impact of John F Kennedy's assassination on Bostonians on the final day of Smith's trial.

Using original transcripts, interviews and historical research Junger tells the story of the two men - one black, one white - in an era of social turmoil. Both came from large, poor families and served in the army. Smith quit school in Mississippi at 14, drifted into alcoholism and burglary, unstable relationships and a hand-to-mouth existence. DeSalvo, son of a violent drunk, graduated from torturing animals in Boston's rough Chelsea district to breaking and entering, voyeurism and rape. He was married to a German woman and had two children.

These men's own words make gripping reading. Questioned by the cops, Smith seems insistent, incredulous. ("I ain't going to take no one's woman, Jesus Christ, especially a white woman, you kidding? ) DeSalvo's confessions ramble chillingly ("I see the back of her head and I was all hot, just like my head was going to blow off".) Sometimes, however, Junger resorts to conjecture: "Roy must have decided..." or "Smith must have drawn a deep breath". Like a juror he gamely tries to make sense of the inconsistencies in both men's versions of the truth.

Junger ultimately votes for Smith's innocence and DeSalvo's credentials as "a good candidate" for the murders. He suggests this may be one of those stories where the most interesting thing is not the truth but "all the things that could be true". Is this the non-fiction writer acknowledging the power of fiction? It's by pursuing all the possibilities, Junger concludes, that we "understand the world in its deepest, most profound sense".