On September 19th, 2001 at the age of 44, Deborah St Germain was murdered in a trailer in Gleeson, Arizona. She had been shot seven times. Her body was discovered by a friend. Ray, her fifth husband, a marine turned cop, had vanished. There was little doubt that he had done it.

The murder was a shock to her two sons but not entirely a surprise. There seemed a sense, at least in retrospect, in which Deborah’s whole life had been leading to something tragic and violent. She had had a string of men, some of them troublesome; at least one beat her. Guns were as common in her life as accessories. Gleeson, where she and Ray spent their last years, was a disused copper camp, a rotting ghost town with collapsing mine shafts and arsenic in the water, without telephone lines or utility services. Of all the dodgy places Deborah had lived, Gleeson was the worst.

Justin St Germain, the younger of Deborah’s sons, was 20 when she died. He tried hard to relegate her death, and his own “white trash” upbringing, to the shadows of his adult life. He finished college in Arizona and moved to California, becoming a Wallace Stegner fellow at Stanford, where he ate organic and attended literary readings at lesbian bars.

“I denied my mother, lied about her death, kept her pictures in boxes, tried not to think of her.”

Unsurprisingly, her death haunted him. A decade later, he writes: “My vision blurs. My hands begin to shake. A burn spreads through my chest. Whatever closure I was hoping to find is never going to come, only more of this same old rage. Since she died, it’s like I’m trapped in a house on fire.”

By this time St Germain has returned to Arizona to revisit the scenes of his past, to meet some of the men who were part of his mother’s life, to rake through police reports – in short, to write this book.

Among the many questions St Germain cannot, finally, answer is how a woman who was in so many ways strong and resourceful – a former army paratrooper who had learned Arabic, a small-business owner, someone who knew how to flip property for a quick profit, an expert with an M16, and “the toughest woman I’ve ever known” – could be so unwise when it came to choosing men.

There was a point, he suggests, at which her life might have gone another way. She had sacrificed a lot for her sons, but by the age of 40 she had some money saved and was free of child-rearing. But, no, a groove had been worn in. “She’d been sacrificing for so long that she didn’t know how to live for herself, and so she gave up everything for yet another man. I couldn’t understand then how she must have felt: alone and abandoned, as if nobody needed her. And there was Ray, a man adrift, a project.”

St Germain aims to embed his mother’s story in the larger tale of the United States’ relationship to violence and its love affair with guns. The family lived in and around Tombstone, one-time home of the Wild West legend Wyatt Earp and site of the gunfight at the OK Corral. “If my mother made a wrong choice, it was moving to a town obsessed with Wyatt Earp, where a former deputy would kill her and other men would say that she deserved it.”

But the parallels he draws often seem strained, the periodic forays into the tale of Wyatt Earp serving mainly to deflate the intensity with which St Germain tells his own family’s story. In attempting to harness his mother’s fate to history, St Germain distracts us from the more haunting and immediate glimpses of everyday violence by which he was surrounded growing up.

When the author was 13 his friend got a pellet gun, a semiautomatic, carbon-dioxide-powered weapon capable of shooting pointed-tip lead pellets more than 300m a second. One day the two boys met some girls from school.

“I saw his face flush red and knew that he was going to shoot them, and in that moment a strange feeling filled me, partly dread and partly glee and partly admiration. I didn’t try to stop him.”

This tension between the admitted lure of violence and an awareness of its terrible effects circles around another question St Germain poses: what kind of man can and should he be in the wake of his mother’s death? What sort of man would she want him to be? How can he avoid becoming the kind of man his mother married?

Son of a Gun is not an anti-gun morality tale, nor does it us offer us new insights into the United States' love affair with weaponry. Its strength lies instead in the author's attempt to understand his mother, to recall the things he loved about her, and to forgive her for the person she was – and in his own journey through loss and rage.

For now, it seems, he is a man who still sleeps with a loaded shotgun under his bed.

“‘I don’t love guns, don’t belong to any organisations, don’t have any bumper stickers,” he writes.

He knows the statistics, and he’s seen first hand what guns can do, but he sleeps with a gun under his bed for one reason: “‘in case there’s a man at the door who means me harm. My friends in San Francisco tell me that if that happens, I should call the police; I tell them that the police won’t show up in time to save them and will only catch their killer half the time. Nobody ever wins the argument. They don’t believe in the man at the door. I do. I’ve met him.”