On 4 March, on what would have been his 30th birthday, Alejandro Nieto’s parents left a packed courtroom in San Francisco, shortly before pictures from their son’s autopsy were shown to a jury. The photographs showed what happens when 14 bullets rip through a person’s head and body. Refugio and Elvira Nieto spent much of the rest of the day sitting on a bench in the windowless hall of the federal building where their civil lawsuit for their son’s wrongful death was being heard.

Alex Nieto was 28 years old when he was killed, in the neighbourhood where he had spent his whole life. He died in a barrage of bullets fired at him by four San Francisco policemen. There are a few things about his death that everyone agrees on: he was in a hilltop park eating a burrito and tortilla chips, wearing the Taser he carried for his job as a bouncer at a nightclub, when someone called 911 on him a little after 7pm on the evening of 21 March 2014. When police officers arrived a few minutes later, they claim Nieto defiantly pointed the Taser at them, and that they mistook its red laser light for the laser sights of a gun, and shot him in self defence. However, the stories of the four officers contradict each other, and some of the evidence.

On the road that curves around the green hilltop of Bernal Heights Park there is an unofficial memorial to Nieto. People walking dogs or running or taking a stroll stop to read the banner, which is pinned by stones to the slope of the hill and surrounded by fresh and artificial flowers. Alex’s father Refugio still visits the memorial at least once a day, walking up from his small apartment on the south side of Bernal Hill. Alex Nieto had been walking on the hill since he was a child: that evening his parents, joined by friends and supporters, went up there in the dark to bring a birthday cake up to the memorial.

Refugio and Elvira Nieto are reserved people, straight-backed but careworn, who speak eloquently in Spanish and hardly at all in English. They had known each other as poor children in a little town in central Mexico and emigrated separately to the Bay Area in the 1970s, where they met again and married in 1984. They have lived in the same building on the south slope of Bernal Hill ever since. She worked for decades as a housekeeper in San Francisco’s downtown hotels and is now retired. He had worked on the side, but mostly stayed at home as the principal caregiver of Alex and his younger brother Hector. In the courtroom, Hector, handsome, sombre, with glossy black hair pulled back neatly, sat with his parents most days, not far from the three white and one Asian policemen who killed his brother. That there was a trial at all was a triumph. The city had withheld from family and supporters the full autopsy report and the names of the officers who shot Nieto, and it was months before the key witness overcame his fear of the police to come forward.

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Nieto died because a series of white men saw him as a menacing intruder in the place he had spent his whole life. They thought he was possibly a gang member because he was wearing a red jacket. Many Latino boys and men in San Francisco avoid wearing red and blue because they are the colours of two gangs, the Norteños and Sureños – but the colours of San Francisco’s football team, the 49ers, are red and gold. Wearing a 49ers jacket in San Francisco is as ordinary as wearing a Saints jersey in New Orleans. That evening, Nieto, who had thick black eyebrows and a closely cropped goatee, was wearing a new-looking 49ers jacket, a black 49ers cap, a white T-shirt, black trousers, and carried the Taser in a holster on his belt, under his jacket. (Tasers shoot out wires that deliver an electrical shock, briefly paralysing their target; they are shaped roughly like a gun, but more bulbous; Nieto’s had bright yellow markings over much of its surface and a 15-foot range.)

Nieto had first been licensed by the state as a security guard in 2007 and had worked in that field since. He had never been arrested and had no police record, an achievement in a neighbourhood where Latino kids can get picked up just for hanging out. He was a Buddhist: a Latino son of immigrants who practised Buddhism is the kind of hybrid San Francisco used to be good at. As a teen he had worked as a youth counsellor for almost five years at the Bernal Heights Neighborhood Center; he was outgoing and participated in political campaigns, street fairs and community events.

He had graduated from community college with a focus on criminal justice, and hoped to help young people as a probation officer. He had an internship with the city’s juvenile probation department not long before his death, according to former city probation officer Carlos Gonzalez, who became a friend. Gonzalez said Nieto knew how criminal justice worked in the city. No one has ever provided a convincing motive for why he would point a gun-shaped object at the police when he knew that it would probably be a fatal act.

Facebook Twitter Pinterest Elvira and Refugio Nieto want justice for their dead son Alex. Photograph: Gabrielle Lurie/The Guardian

On the evening of 21 March 2014, Evan Snow, a thirtysomething “user experience design professional”, according to his LinkedIn profile, who had moved to the neighbourhood about six months earlier (and who has since departed for a more suburban environment), took his young Siberian husky for a walk on Bernal Hill.

As Snow was leaving the park, Nieto was coming up one of the little dirt trails that leads to the park’s ring road, eating chips. In a deposition prior to the trial, Snow said that with his knowledge of the attire of gang members, he “put Nieto in that category of people that I would not mess around with”.

His dog put Nieto in the category of people carrying food, and went after him. Snow never seemed to recognise that his out-of-control dog was the aggressor: “So Luna was, I think, looking to move around the benches or behind me to run up happily to get a chip from Mr Nieto. Mr Nieto became further – what’s the right word? – distressed, moving very quickly and rapidly left to right, trying to keep his chips away from Luna. He ran down to these benches and jumped up on the benches, my dog following. She was at that point vocalising, barking, or kind of howling.”

The dog had Nieto cornered on the bench while its inattentive owner was 40 feet away – in his deposition for the case, under oath, his exact words were that he was distracted by a female “jogger’s butt”. “I can imagine that somebody would – could assume the dog was being aggressive at that point,” Snow said. The dog did not come when he called, but kept barking. Nieto, Snow says, then pulled back his jacket and took his Taser out, briefly pointing at the distant dog-owner before he pointed it at the dog baying at his feet. The two men yelled at each other, and Snow apparently used a racial slur, but would not later give the precise word. As he left the park, he texted a friend about the incident. His text, according to his testimony, said, “in another state like Florida, I would have been justified in shooting Mr Nieto that night” – a reference to that state’s infamous “stand your ground” law, which removes the obligation to retreat before using force in self-defence. In other words, he apparently wished he could have done what George Zimmerman did to Trayvon Martin: execute him without consequences.

Soon after, a couple passed by Nieto. Tim Isgitt, a recent arrival in the area, is the communications director of a nonprofit organisation founded by tech billionaires. He now lives in suburban Marin County, as does his partner Justin Fritz, a self-described “email marketing manager” who had lived in San Francisco about a year. In a picture one of them posted on social media, they are chestnut-haired, clean-cut white men posing with their dogs, a springer spaniel and an old bulldog. They were walking those dogs when they passed Nieto at a distance.

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Fritz did not notice anything unusual but Isgitt saw Nieto moving “nervously” and putting his hand on the Taser in its holster. Snow was gone, so Isgitt had no idea that Nieto had just had an ugly altercation and had reason to be disturbed. Isgitt began telling people he encountered to avoid the area. (One witness who did see Nieto shortly after Isgitt and Fritz, longtime Bernal Heights resident Robin Bullard who was walking his own dog in the park, testified that there was nothing alarming about him. “He was just sitting there,” Bullard said.)

At the trial, Fritz testified that he had not seen anything alarming about Nieto. He said that he called 911 because Isgitt urged him to. At about 7.11pm he began talking to the 911 dispatcher, telling her that there was a man with a black handgun. What race, asked the dispatcher, “black, Hispanic?” “Hispanic,” replied Fritz. Later, the dispatcher asked him if the man in question was doing “anything violent”, and Fritz answered, “just pacing, it looks like he might be eating chips or sunflowers, but he’s resting a hand kind of on the gun”. Alex Nieto had about five more minutes to live.

San Francisco was never anti-newcomer: until recently, it had always been a place where new people arrived to reinvent themselves. When they arrive in a trickle, they integrate and contribute to the ongoing transformation. When they arrive in a flood, as they have during economic booms since the 19th-century gold rush, including the dotcom surge of the late 1990s and the current tech tsunami, they scour out what was there before. By 2012 the incursion of tech workers had gone from steady stream to deluge, and more and more people and institutions – bookstores, churches, social services, bars, small businesses – began to be evicted.

San Francisco had been a place where some people came out of idealism or stayed to realize an ideal: to work for social justice or teach the disabled, to write poetry or practise alternative medicine – to be part of something larger than themselves that was not a corporation, to live for something more than money. That was becoming less and less possible as rent and sale prices for homes spiralled upward. What the old-timers were afraid of losing, many of the newcomers seemed unable to recognise. The tech culture seemed in small and large ways to be a culture of disconnection and withdrawal. And it was very white, very male and pretty young, which is why I started to call my hometown “Fratistan”. (As of 2014, Google’s Silicon Valley employees, for example, were 2% black, 3% Latino, and 70% male.)

Tech companies created billionaires whose influence warped local politics, pushing for policies that served the new industry and their employees at the expense of the rest of the population. None of the money sloshing around the city trickled down to preserve the centre for homeless youth that closed in 2013, or the oldest black-owned black-focused bookstore in the country, which closed in 2014, or San Francisco’s last lesbian bar, which folded in 2015, or the African Orthodox Church of St John Coltrane, which is now facing eviction from the home it found after an earlier eviction during the late-1990s dotcom boom. Resentments rose. And cultures clashed.

Facebook Twitter Pinterest Bernal Heights Park in San Francisco, Cailifornia. Photograph: Justin Sullivan/Getty Images

At 7.12pm on the evening of 21 March, the police dispatcher who had spoken to Fritz put out a call. Lieutenant Jason Sawyer and officer Richard Schiff, a rookie who had been in the job for less than three months, responded and headed for Bernal Heights Park. They tried first to enter it in their patrol car from the south side, the side where Alex’s parents lived, then turned around and drove in from the north side, going around the barrier that keeps vehicles out and heading up the road that is often full of runners, walkers and dogs at that time of day. They moved rapidly, but without lights or sirens; they were not heading into an emergency. At 7.17:40pm Alejandro Nieto came walking downhill around a bend in the road, according to the 911 conversation with Fritz. At 7.18:08pm, another policeman in the park, but not at the scene, broadcast: “Got a guy in a red shirt coming toward you.” Schiff testified in court, “Red could be related to a gang involvement. Red is a Norteño colour.”

Schiff testified that from about 90ft away he shouted “Show me your hands” and that Nieto had replied, “No, show me your hands”, then drew his Taser, assuming a fighting stance, holding the weapon in both hands pointed at the police. The officers claim that the Taser projected a red light, which they assumed was the laser sight of a handgun, and feared for their lives. At 7.18:43pm, Schiff and Sawyer began barraging Nieto with .40-calibre bullets.

At 7.18:55pm, Schiff shouted “red”, a police code word for out of ammunition. He had emptied a whole clip at Nieto. He reloaded, and began shooting again, firing 23 bullets in all. Sawyer was also blazing away. He fired 20 bullets. Their aim appears to have been sloppy, because Fritz, who had taken refuge in a grove of eucalyptus trees below the road, can be heard shouting “Help! Help!” on his call to the 911 operator, as bullets fired by the police were “hitting the trees above me, breaking things and just coming at me”.

Sawyer said: “Once I realised there was no reaction, none at all after being shot, I picked up my sights and aimed for the head.” Nieto was hit just above the lip by a bullet that shattered his right upper jaw and teeth, another ripped through both bones of his lower right leg. Though the officers testify that he remained facing them, that latter bullet went in the side of his leg, as though he had turned away. It is unlikely that a person could stand on a leg injured like that.

Schiff shouted 'red', a police code word for out of ammunition. He had emptied a whole clip at Nieto

Two more officers, Roger Morse and Nate Chew, drove up to the first patrol car, got out and drew their guns. There was no plan, no communications, no strategy to contain the suspect or capture him alive if he proved to be a menace, to avoid a potentially dangerous confrontation in a popular park where bystanders could be hit. Morse testified in court: “When I first arrived I saw what appeared to be muzzle flash. I aimed at him and began shooting.” Tasers produce nothing that resembles muzzle flash. Chew testified that Nieto was already on the ground when they arrived. He fired five shots at the man on the ground. He told the court he stopped when “I saw the suspect’s head fall down to the pavement”.

Several more bullets hit Nieto while he was on the ground– at least 14 struck him, according to the city autopsy report. One went into his left temple and tore through his head toward his neck. Several hit him in the back, chest, and shoulders. One more went into the small of his back, severing the spinal cord.

The officers approached Nieto at 7.19:20pm, less than two minutes after it had all begun. Morse was the first to get there; he says that Nieto’s eyes were open and that he was gasping and gurgling. He says that he kicked the Taser out of the dying man’s hands. Schiff says he “handcuffed him, rolled him over, and said, ‘Sarge, he’s got a pulse.’” By the time the ambulance arrived, Alejandro Nieto was dead.

Nieto’s funeral, on 1 April 2014, packed the little church in Bernal Heights that his mother had taken him to as a child. I went with my friend Adriana Camarena, a gregarious lawyer from Mexico City who lives in the Mission District, the neighbourhood on Bernal’s north flank. She had met Alex briefly; I never had. We sat near a trio of African-American women who had lost their own sons in police killings and routinely attend the funerals of other such victims. Adriana had become close to Refugio and Elvira Nieto. Their son had been their ambassador to the English-speaking world, and gradually Adriana was drawn into their grief and their need. She stepped in as an interpreter, advocate, counsel and friend. Benjamin Bac Sierra, a former marine who teaches writing at San Francisco’s community college, was a devoted friend of and mentor to Alex. He has become the other leader of a small coalition named Justice for Alex Nieto.

In that springtime of Nieto’s death, I had begun to feel that what was tearing my city apart was not only a conflict pitting long-term tenants against affluent newcomers and the landlords, estate agents, house-flippers, and developers seeking to open up room for them by shoving everyone else out. It was a conflict between two different visions of the city.

What I felt strongly at the funeral was the vital force of real community: people who experienced where they lived as a fabric woven from memory, ritual and habit, affection and love. This was a measure of place that had nothing to do with money and ownership and everything to do with connection. Adriana and I turned around in our pew and met Oscar Salinas, a big man who was native to the Mission. He told us that when someone in the community is hurt, the Mission comes together. “We take care of each other.” To him, the Mission meant the people who shared Latino identity and a commitment to a set of values, and to each other, all held together by place.

In the spring of Nieto's death, I began to feel that a conflict between two visions of the city were tearing it apart

The sense of community people were trying to hang on to was about the things that money cannot buy. It was about home as a whole neighbourhood and the neighbours in it, not just the real estate you held title to or paid rent on. It was not only the treasure of Latinos; white, black, Asian and Native American residents of San Francisco had long-term relationships with people, institutions, traditions, particular locations. “Disruptive” has been a favourite word of the new tech economy, but old-timers saw communities, traditions, and relationships being disrupted. Many of the people being evicted and priced out were the people who held us all together: teachers, nurses, counsellors, social workers, carpenters and mechanics, volunteers and activists. When, for example, someone who worked with gang kids got driven out, those kids were abandoned. How many threads could you pull out before the social fabric disintegrated?

Two months before the funeral, the real-estate website Redfin looked at the statistics and concluded that 83% of California’s homes, and 100% of San Francisco’s, were unaffordable on a teacher’s salary. What happens to a place when the most vital workers cannot afford to live in it? Displacement has contributed to deaths, particularly of the elderly. In the two years since Nieto’s death, there have been multiple stories of seniors who died during or immediately after their eviction. Gentrification can be fatal.

It also brings newcomers to neighbourhoods with nonwhite populations, sometimes with atrocious consequences. Local newspaper The East Bay Express recently reported that in Oakland, recently arrived white people sometimes regard “people of color who are walking, driving, hanging out, or living in the neighborhood” as “criminal suspects.” Some use the website Nextdoor.com to post comments “labeling Black people as suspects simply for walking down the street, driving a car, or knocking on a door.” The same thing happens in the Mission, where people post things on Nextdoor such as “I called the police a few times when is more then three kids standing like soldiers in the corner.” What’s clear in the case of Nieto’s death is that a series of white men perceived him as more dangerous than he was and that he died of it.

Facebook Twitter Pinterest Benjamin Bac Sierra, one of Alex Nieto’s best friends and co-leader of the Justice for Alex Nieto campaign. Photograph: Gabrielle Lurie/The Guardian

On 1 March 2016, the day the trial began, hundreds of students at San Francisco public schools walked out of class to protest against Nieto’s killing. A big demonstration was held in front of the federal courthouse, with drummers, Aztec dancers in feathered regalia, people holding signs, and a TV station interviewing Nieto’s friend Benjamin Bac Sierra. Nieto’s face on posters, banners, T-shirts and murals had become a familiar sight in the Mission; a few videos about the case had been made, demonstrations and memorials had been held. For some, Nieto stood for victims of police brutality and for a Latino community that felt imperilled by gentrification, by the wave of evictions and the people who regarded them as menaces and intruders in their own neighbourhood. Many people who cared about the Nietos came to the trial each day, and the courtroom was usually nearly full.

Trials are theatre, and this one had its dramas. Adante Pointer, a black lawyer with the Oakland firm of John Burris, which handles a lot of local police-killing lawsuits, represented Refugio and Elvira Nieto, the plaintiffs. Their star witness, Antonio Theodore, had come forward months after the killing. Theodore is an immigrant from Trinidad, a musician in the band Afrolicious, and a resident of the Bernal area. An elegant man with neat shoulder-length dreads who came to court in a suit, he said he had been on a trail above the road, walking a dog, and that he had seen the whole series of events unfold. He testified that Nieto’s hands were in his pockets – that he had not pointed his Taser at the officers, there was no red laser light; the officers had just shouted “stop” and then opened fire.

When Pointer asked him why he had not come forward earlier, he replied: “Just think: it would be hard to tell an officer that I just saw fellow officers shooting up somebody. I didn’t trust the police.” Theodore testified cogently under questioning from Pointer. But the next morning, when city attorney Margaret Baumgartner, an imposing white woman with a resentful air, questioned him, he fell apart. He contradicted his earlier testimony about where he had been and where the shooting took place, then declared that he was an alcoholic with memory problems. He seemed to be trying to make himself safe by making himself useless. Pointer questioned him again, and he said: “I don’t care to be here right now. I feel threatened.”

The details of what had happened were hotly debated and often contradictory, especially with regard to the Taser. The police had testified as though Nieto had been a superhuman or inhuman opponent, facing them off even as they fired again and again, then dropping to a “tactical sniper posture” on the ground, still holding the Taser with its red laser pointing at them. The city lawyers brought in a Taser expert whose official testimony seemed to favour them, but when he was asked by Pointer to look at the crime‑scene photos, he said the Taser was off and that it was not something easily or accidentally turned on or off. The light is only on when the Taser is on. Officer Morse had testified that when he arrived to kick it out of Nieto’s hands there was no red light or wires coming from it. The Taser wires are, however, visible in the police photographs documenting the scene.

One piece of evidence produced was a fragment of bone found in the pocket of Nieto’s jacket. Some thought this proved that his hands had been in his pockets, as Theodore said. Dr Amy Hart, the city coroner, said in the trial on Friday, 4 March, that there were no photographs of his red 49ers jacket, which must have been full of bullet holes. The following Monday, an expert witness for the city mentioned the photographs of the jacket that the city had supplied him. The jurors were shown photographs of Nieto’s hat, which had a bullet hole in it that corresponded to the hole in his temple, and of his broken sunglasses lying next to a puddle of blood. The coroner testified to abrasions on Nieto’s face consistent with Nieto wearing glasses. Before this evidence was shown, Officer Richard Schiff had testified under oath that he made eye contact with Nieto and saw his forehead pucker up in a frown. If the dead man had been wearing a hat and glasses, then Schiff was mistaken that he saw those things.

When Elvira Nieto testified about her devastation at the death of her son, Pointer asked her about her husband’s feelings as well. “Objection,” shouted Baumgartner, as though what a wife said about her husband’s grief should be disqualified as hearsay. The judge overruled her. At another point, Justin Fritz apologised to the Nietos for the outcome of his 911 call and seemed distressed. Refugio Nieto allowed Fritz to hug him; his wife did not. “Refugio later said that at that moment he was reminded of Alex’s words,” Adriana told me, “that even with the people that we have conflict with, we need to take the higher ground and show the best of ourselves.”

Adriana sat with the Nietos every day of the trial, translating for them when the court-appointed translator was off duty. Bac Sierra, in an impeccable suit and tie, was right behind them every day, in the first of three rows of benches usually full of friends and supporters. Nieto’s uncle often attended, as did Ely Flores, another young Latino who was Nieto’s best friend and a fellow Buddhist.

Facebook Twitter Pinterest Elvira and Refugio Nieto take part in a protest march. Photograph: Steve Rhodes/Demotix/Corbis

It was a civil trial, so the standard was not “beyond a reasonable doubt”, just the “preponderance of evidence”. No one was facing prison, but if the city and officers were found liable, there could be a large financial settlement and it could affect the careers of the policemen. The trial was covered by several local media outlets. On Thursday 10 March, after an afternoon and morning of deliberations, the eight jurors – five white, one Asian woman and two Asian men – unanimously ruled in favour of the police on all counts.

Flores wept in the hallway. The American Civil Liberties Union of Northern California published a response to the verdict headlined, “Would Alex Nieto Still Be Alive if He Were White?” Police are now investigating claims that Officer Morse posted a sneering attack on Nieto on a friend’s Facebook page that night.

San Francisco is now a cruel place and a divided one. A month before the trial, the city’s mayor, Ed Lee, decided to sweep the homeless off the streets for the Super Bowl, even though the game was played 40 miles away, at the new 49ers stadium in Silicon Valley. Online rants about the city’s homeless population have become symptomatic of the city’s culture clash. The open letter to the mayor published in mid-February by Justin Keller, founder of a not very successful startup, was typical in tone: “I know people are frustrated about gentrification happening in the city, but the reality is, we live in a free market society. The wealthy working people have earned their right to live in the city. They went out, got an education, work hard, and earned it. I shouldn’t have to worry about being accosted. I shouldn’t have to see the pain, struggle, and despair of homeless people to and from my way to work every day.” And like Evan Snow, who wanted to blow away Alejandro Nieto after their encounter, Keller got his wish in a way. Pushed out of other areas, hundreds of homeless people began to set up tents under the freeway overpass around Division Street on the edge of the Mission, a gritty industrial area with few residences. The mayor destroyed this rainy-season refuge too: city workers threw tents and belongings into dump trucks and hounded the newly propertyless onward. One of the purges came before dawn the morning the Nieto trial began.

When the trial ended with a verdict in favour of the police, 150 or so people gathered inside at the Mission Cultural Center and outside on rainy Mission Street. People were composed, resolute, disappointed, but far from shocked. It was clear that most of them had never counted on confirmation from the authorities that what happened to Alex Nieto was wrong. They did not need that validation. Their sense of principle and history was not going to be swayed by this verdict, even if they were saddened or angered by it. Bac Sierra, out of his courtroom suits and in a T-shirt and cap, spoke passionately, as did Oscar Salinas, who had just posted on Facebook the words: “Alex you will never be forgotten, your parents will always be taken care of by us, the community. As I’ve always said, the unspoken word of La Mision is when someone is hurting, needs help, or passes we come together as a family and take care of them.”

The Nietos spoke, with Adriana translating for those who did not understand Spanish. And Adriana spoke on her own behalf: “One of the most important changes in my path being involved in the Alex Nieto case has been to learn more about restorative practices, because as someone trained in legal systems, I know that the pain and fear that we are not safe from police in our communities will not go away until there is personal accountability by those who harm us.”

Fear that we aren't safe from police in our communities won't go away until there's accountability by those who harm us Adriana Camarena

Adriana, her historian husband, and their friends – including an Aids activist and a choreographer – who live nearby in a ramshackle old building, had faced their own eviction battle last year, and won it. But the community that came together that night was still vulnerable to the economic forces tearing the city apart. Many of these people may have to move on soon, some already have.

The death of Alex Nieto is a story of one young man torn apart by bullets, and of a community coming together to remember him. They pursued more than justice, as the case became a cause, as the expressions became an artistic outpouring in videos, posters, and memorials, and as friendships and alliances were forged and strengthened. Adriana Camarena told the crowd: “Our victory, as the Nietos said yesterday, is that we are still together.”

Main photograph: Gabrielle Lurie for the Guardian

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• This article was amended on 29 March 2016. An earlier version said incorrectly that Justin Fritz had described Nieto to a 911 dispatcher as “probably foreign”. That was based on a mishearing of a recording of the call. In fact Fritz was describing Nieto’s height and said he was “probably six-one”. We apologise for the error.