The American crime writer James Ellroy, born Lee Earle Ellroy, chose his pen name because it was ‘simple, concise and dignified – things I am not’, a statement perhaps underscored by another name he likes being called, ‘Demon Dog’. We learn from Steven Powell’s sober new biography that an overseas publisher who wanted to translate Ellroy’s work (‘an almost unendurable wordstorm of perversity and gore,’ according to one critic) found that translators, deterred by his difficult language and right-wing sympathies, refused to do it.

Ellroy started to read crime fiction as a boy in 1950s Los Angeles when his estranged father gave him Mickey Spillane’s Mike Hammer books to read while looking after him at weekends. His youth was a troubled one: drink, drugs, jail. In his thirties, he began writing a novel so as not to be bested by a friend who told him he was writing one himself. Initially he worked under the spell of Thomas Harris’s Hannibal Lecter novels, the sales of which Ellroy eyed keenly. Later, he added counterfactual conspiracy theory to grisly suspense after falling for the blur of fact and fiction in Don DeLillo’s Libra (1988), about Lee Harvey Oswald.

Behind everything lay the unsolved murder of Ellroy’s mother, Jean, in 1958, when he was ten. It was the source of a lifelong obsession with another cold case, the murder of 22-year-old Elizabeth Short, the ‘Black Dahlia’, the subject of his 1987 crime novel of that name, of which Powell says: ‘Surface is essential in this world, speaking as it does to success but also when penetrated, exposing twisted sexual desires and psychotic motivations.’ One might feel it is no bad thing that, on the whole, Powell prefers to summarise Ellroy’s novels rather than analyse them. The insights of this book come from the information it offers. We are reminded that the novelist’s trademark style, a telegraphic staccato that influenced the crime novels of David Peace, was not simply an aesthetic choice. Encouraged to condense the unwieldy storyline of American Tabloid (1995) in order to deliver the novel at publishable length, Ellroy chose instead to cut swathes of connective tissue from his sentences.

Away from the books, well, where do you begin? Powell avoids praise or blame but makes clear there is no shortage of grounds for the latter. Ellroy broke into the homes of girls in his class at high school to steal their underwear. Fame was no corrective. A woman he dated in 1986 disliked his jokes about using ‘the names of his ex-girlfriends as dead hookers in his novels … These were often the same women he had dedicated novels to when the relationship was going well.’ A few years after she and Ellroy had gone their separate ways, she duly found her name given to a murdered prostitute in LA Confidential (1990).

Powell does not set out to expose Ellroy, who has always been perfectly happy to expose himself. If anything, you sense Powell feels safer discussing his subject’s sexual conduct than his right-wing (sometimes far-right) views, which are mostly attributed to an understandable hunger for attention in his youth. ‘With any feelings of anti-Semitism long behind him, Ellroy enjoyed taking in the culture at the Hillcrest’ (his local golf club in Los Angeles) is one of a number of sentences that sow doubt rather than eliminate it.

Overall, though, Powell’s unruffled approach is a shrewd way of tackling Ellroy’s sensational life and imagination. Often a mordant humour glints. Of the manuscript of Ellroy’s 1984 novel Blood on the Moon, initially titled ‘LA Death Trip’, Powell says that a literary agent ‘questioned why the novel ends with the lead protagonist, Detective Lloyd Hopkins, committing suicide with a rocket launcher at the Silverlake power plant in his confrontation with the serial killer, Theodore Verplanck’. (Ellroy answered his queries with what looked like, in the agent’s words, ‘a kidnap letter. It was written in red pencil on yellow legal paper, and some of the words on it were like an inch high: I AM NOT GOING TO DO THIS.’)

Clearly, Ellroy is a canny operator. He gave back his publishers his advance for The Black Dahlia on the condition that they spend it on the book’s publicity and double their own marketing budget for the novel. When it was suggested that he talk up ‘the novel’s emotional connection to his mother’s murder’, he obliged. It all helped Ellroy secure the kind of coverage that propelled him into the top rank of American novelists; Powell reports Ellroy’s delight when Time chose American Tabloid as 1995’s best novel, ahead of Philip Roth’s Sabbath’s Theater.

It is a mark of Powell’s honesty that he should quote Ellroy on his desire to have Adam Sisman or Tom Nolan, authors of lives of John le Carré and Ross Macdonald respectively, write his biography. A wise head told Ellroy he should get a writer who had actually written on him; soon afterwards Powell, author and editor of several scholarly works on Ellroy, was leaving him voicemail messages announcing his intentions. The resulting book earns its keep with a wealth of detail. At one point, the illustrator and designer Chip Kidd, who has worked on many of Ellroy’s titles, recounts confiding in Ellroy that he was being harassed by a former lover. Ellroy said it would soon blow over, and if not, he would get ‘some guys in New York’ to sort things out. ‘No other author has offered to threaten my ex-boyfriend!’ Kidd says. You can believe it.