Jill Leovy became crime correspondent of the Los Angeles Times in 2002. For much of the next decade she was on the frontline of the “homicide epidemic” that gripped the southern districts of the city, the poor and mostly black and Hispanic neighbourhoods of Watts and Compton. Many of the murders were a symptom of the ongoing territorial gang violence of the previous two decades. A very high proportion were murders of young black men by other young black men. Most of these murders went unreported even in the LA Times. Some of the policemen that Leovy talked to had a bleakly ironic term for such “black on black” crime: NHI (“no human involved”). Very few of the murder investigations resulted in a conviction.

Leovy sought to change that emphasis, humanise all of the city’s crimes. She persuaded her editors at the LA Times to run an online homicide report in which every murder victim in the city was identified and the circumstances of their death recorded along with as much personal detail as Leovy could provide. In this way, under the banner “a story for every victim”, Leovy documented 1,133 murders in 2004 alone. That homicide rate, mirrored in other cities, was, Leovy discovered at first hand, the story that America did not want to hear, mired as it seemed to be in racial politics.

She was determined, however, as David Simon (creator of The Wire) had been in Baltimore, to try to begin to explain that story in all of its complexity. She developed the understanding – after years embedded with the homicide detectives of the LAPD, and in close contact with the families of victims – that LA’s excessive murder rate was a result of “under-policing” – and not, as one prevailing liberal narrative suggested, the consequence of heavy-handed law enforcement. The comparative lack of resources directed at this “epidemic”, the inbuilt assumptions of the catch-all term “gang-related”, meant that the crimes were necessarily taken less seriously at every level. Except, that is, Leovy discovered, by a handful of very dedicated detectives who were determined to investigate every single murder as if it were “the hottest celebrity crime in town”. One such detective was John Skaggs, whose whole working life, she suggests, was directed to one end: “making black lives expensive.” Skaggs, a white American, of Irish descent, becomes one hero of Ghettoside, Leovy’s book about her decade as a crime reporter. In particular she dwells on his investigation into the 2007 murder of Bryant Tennelle, the 18-year-old son of one of Skaggs’s fellow detectives in the force, Wally Tennelle, a man for whom such a horror was all too familiar. I spoke to her on the phone last week about her compulsion to tell LA’s murder story.

One of the more uncomfortable aspects of journalism is that some people’s tragedies are more newsworthy than others. When you conceived of the Los Angeles Times homicide report, it was presumably a reaction to that fact?

Yes. It is the most political thing in the world to identify who the victims are in any situation. The numbers are very important. They really are outsized and strange in terms of the racial disproportion of victimisation. And I did think it was appropriate to show what those numbers meant. The homicide report was one of the last things I tried to highlight it. I had done the standard mix of beat stories and narrative pieces. I wanted to find another way to get the attention of people.

Did the police support the report? I mean here were mostly unsolved murders, stacking up, suddenly being given a more shocking human face…

They were supportive. On and off. You would sometimes piss them off and the atmosphere would change. But cops, especially line cops, were desperate to see it covered. A lot of what I exploited was their hunger to see this story told. They were constantly intrigued by what it meant themselves. It is a baffling world. It makes your thoughts spin.

Those terms they sometimes used, “no human involved” to describe these murders, and so on. What was the tone of that?

I didn’t hear that phrase much in the present. It was told mostly as a memory by cops who had been there a long time. It was more a 1970s, 1980s thing. It was used as a sort of ironic commentary on the outside world’s view of these murders. The cops often felt insulted I think, though they were not that good at expressing it, by the public indifference to the world they are confronting and living with every day. There is a lot of black humour that emanates from that. You scrape it away and it is really pain they are expressing.

The cops often felt insulted by the public indifference to the world they are confronting and living with every day Jill Leovy

They were angry too, presumably, or at least many of them were, at the idea of being viewed as institutionally racist?

The story of this problem being about racist police officers is way too simple. You would love it to be that simple in a way because it would be easier to fix. The people I know worked there for 20 years because they liked it. They liked the people. It was not uncommon for officers in south LA to be in mixed marriages for example. It is quite a complicated world.

You convey their attitude to the work as an addiction, as well as their sense of mission. Is that how they viewed it?

I often think of two of the officers I don’t really write about – a husband and wife who worked there. She was shot one night and paralysed from the waist down, and he was one of the first officers on the scene. When he came back to work after family leave one of his first cases was a woman in her 20s who had been hit by a stray bullet and paralysed from the waist down. He talked to me about how that on some very deep level solving these crimes was now a mission for him. I offer that anecdote because it never serves to be dismissive of people’s motivation. There is often a lot going on with these people.

These are very tough things to confront every working day – did you also have that sense of mission?

People used to say: “Doesn’t it make you depressed?” And I would say: “Yes, that’s why I do it.” I have to say the homicide beat was the best job I ever had in journalism. I had a very clear idea in my mind why I was there. You don’t get that a lot in life. One of the things about homicide is that it is pretty clear who to sympathise with. It is not heroic to be anti-murder. I know you are not supposed to take sides as a journalist, but I felt it was OK to take sides with people whose children were being murdered. I felt they deserved a little more consideration.

These people, you suggest, were particularly ill-served by the wider cultural indifference that did – and does – not make the solving of these murders a priority. That dereliction of duty feels not so much the police’s problem as American society’s problem?

Yes. The LAPD is set up to be the bureaucracy to end all bureaucracies. They had mandates and priorities coming from so many directions. If you put all those wider demands together this is the police department you get. The fact is though that solving crimes is how you build something long term that leads to a more lawful society. That is easily forgotten.

Facebook Twitter Pinterest A man suspected of being a gang member is searched by LAPD officers. Photograph: Robert Nickelsberg/Getty Images

The police killings of Eric Garner and Michael Brown have moved law enforcement up the political agenda. Do you think that protest and debate will change things?

I guess I do have some issues with the police shootings being the priority. I think we need to understand the reasons why. I quote the Swedish social scientist Gunnar Myrdal in my book, who came as an outsider to the US in the 40s and did an amazing study of the Jim Crow society of the south. He wrote about the low conviction rates for black-on-black crimes and said “leniency in this context is a form of discrimination”. I think that is an idea that has still not occurred to many people in the US. Yes, oppressive criminal justice can clearly be discriminatory and unfair, but leniency can also be unfair to people. It leads to what I have seen in LA, where a black mother loses her child and calls the detective unit three weeks later and they don’t even know who is in charge of the case.

Given the figures for homicides in the past three decades, it seems bizarre that most Americans seem to believe terror only arrived with 9/11…

I started writing in the aftermath of 9/11 and in the streets of south LA it was something I heard all the time: “Nobody is filling newspapers with pictures of our victims”; “My son’s face is not on CNN.” Where was the talk of this national tragedy? Black grief in this country does still not seem to be taken as seriously as white grief. You know, I had one black mother who had lost her son say to me: “We are supposed to be tougher – because we are black.” That is something real.

In the past few years there has been quite a sharp decline in the numbers of murders. Do you think the policy of mass incarceration – 2.3 million Americans in prison – has been a cause of that?

I would put that quite far down the list of factors. It makes the victims safer. But in terms of reaching single adult black males who are really at the eye of this storm? One big change has been the extension of disability and supplemental security income (SSI) to people leaving prison. Want matters – when you don’t have enough money to get food or your kids’ diapers, a commonly shoplifted item in south LA – then you are willing to do desperate things. SSI has allowed these guys to be solitary, to not have to get back with their buddies to survive.

In among all of the cases did the Bryant Tennelle case immediately strike you as a representative story?

They are all like that when you get deep into them. But I think Detective Skaggs was trying to tell me about this case a lot before I started really listening to him. It was very important to him. It worked well for what I was trying to exemplify in the book, which was a detective putting their all into a case and the difference it made.

If you hear that term 'gang-related', remember that in one in three cases the victim has no involvement with a gang Jill Leovy

And also the entirely arbitrary nature of Bryant Tennelle as a victim – he was wearing the wrong hat in the wrong place?

In 2008 I did my own little survey of all the homicides in the city; I talked to the detective in each case. One of the questions I asked was: “If this was a gang-related homicide, was the victim really a combatant? Or was it more random?” All these victims were black or Latino young men, so they fitted one aspect of the profile, but when you looked at it, fully one-third of them were not combatants at all. Wrong place wrong time, or mistaken for someone else, or collateral damage. If you hear that term “gang-related”, it is worth remembering that in one in three cases the victim has no involvement at all with a gang.

I suppose David Simon’s work, which led to The Wire, has been a touchstone in writing this story?

I don’t know if I should admit this but I have never read David Simon’s book and have never seen The Wire. I deliberately did that because I wanted my own vision.

Do you think the fact that these events become drama almost before they become news reports gets in the way of people confronting the reality?

I do. We are so drowning in fantasies about crime, I do think that. But you know, I use narrative as a device too, to make my book readable. I believe in storytelling as a serious way to interrogate reality. It is a tool like science for understanding the world. Violence is very painful to look at. Not the bodies but the months after. The mothers who call me two years later to say they are thinking of killing themselves. The people who never leave their homes again. It is really depressing. There is a flinching that goes on when you face these things, and almost from the moment you succumb to the temptation to dramatise in any way you are succumbing to the temptation to flinch. You instinctively emphasise the parts that are not depressing and dreary. It is really hard to tell the truth about violence, but as a writer you better be exerting yourself every second to do it.

At the time, was it hard to convey that sense to friends and family outside of this world of journalism and police?

My family would roll their eyes at that idea – I put them through it. But yes, this world is a walled city, and the hardest thing is to try to explain to someone on the outside and have them not understand. You feel angry, you feel resentful. I think cops are often misunderstood. It is very painful to be misunderstood about this, as it is in any life that involves trauma or combat. It’s like in Kurt Vonnegut’s book Slaughterhouse-5, about the bombing of Dresden, he only mentions the firebombing a couple of times, but the whole book is about it; with violence you end up talking about everything else but violence.

With the homicide numbers falling – “only” 558 last year – is there now a sense that this is no longer the crisis that it was, that a chapter is closing?

I don’t think it is the crisis it was. But what the city experienced in the past 30 years needs to be recorded. I have a file with 20,000 names on it from LA county going back to the 1980s. That matters and I do want people to know that. It has shaped our world.

Ghettoside is published by Bodley Head on Thursday, £16.99. To order it for £13.59 click here