It was a gift that would change Alfonso Margarito Martínez Esquivel’s life and illuminate some of the darkest moments of Mexico’s recent history: a secondhand Canon SLR bought from a photographer called Goofy.

Through its lens the Mexican photojournalist would witness his country’s slide into drug-fuelled carnage – bodies strung from bridges, dumped on sidewalks, dismembered, burned – without ever losing his trademark grin.

“Margarito was a sweetie – a sweetie to everyone,” said Bibi Gutiérrez, his close friend and mentor, her voice breaking as she remembered giving Martínez one of his big breaks in journalism by buying him his first professional camera. “He was always smiling.”

Murdered in Mexico: the final interview with a legendary journalist – video

As the start of Mexico’s 2006 “war on drugs” plunged parts of their country into a grotesque frenzy of violence, Martínez and Gutiérrez stood together on the frontline, racing to gunfights and massacres to expose the scale of the horror.

“There were corpses everywhere. Machine guns. AK-47s … it was a frightful slaughter,” Gutiérrez said of one notorious shootout where they found themselves tiptoeing around more than a dozen bodies, some people taking their final breaths.

Martínez would cover countless killings over the coming years, earning his reputation as Tijuana’s premier street-level police reporter – a local legend who helped visiting journalists from around the world, including from the Guardian.

Then, at lunchtime on 17 January this year, as the 49-year-old set off from his home on Tijuana’s gritty southside, the crime scene came to him.

Margarito Martínez Esquivel removes a flak jacket from the boot of his car. Photograph: Emilio Espejel/The Guardian

Details of what happened next are still emerging but investigators reportedly believe that as Martínez approached his car, three shots were fired. “It’s done,” the assassin’s accomplice, loitering nearby, informed the gangster suspected of ordering the hit over WhatsApp.

Martínez’s teenage daughter and wife ran outside and found him in agony on the potholed road, blood gushing from his neck. “What cowards,” Gutiérrez, 57, said of her friend’s killers. “Like all of us, Margarito defended himself with a pen, a notebook, a telephone and a camera while these murderers use guns that take away your life.”

As Martínez’s wife cradled her dying husband, local reporters exchanged messages questioning his unusual radio silence. “Ay Dios,” one exclaimed after confirmation of his death. “It can’t be! … Holy God … The horror … Fucking hell … What should we do?”

Journalists across Mexico are asking the same question after a wave of murders targeting their colleagues in what was already one of the world’s most dangerous countries for the press.

At least eight Mexican journalists have been killed this year, prompting an outpouring of anguish and anger that has been exacerbated by a politically charged feud with Mexico’s media-bashing president, Andrés Manuel López Obrador (Amlo).

Six days after Martínez’s slaying, another well-known Tijuana reporter, Lourdes Maldonado, was murdered outside her home. Two years earlier she had publicly told López Obrador she feared for her life.

Police tape surrounds the Tijuana home of murdered journalist Lourdes Maldonado who was gunned down there in January. Photograph: Emilio Espejel/The Guardian

“She was cool, she never fucked around with no one,” one of Maldonado’s neighbours said as he sipped a Sunday afternoon can of watery Mexican beer near the glass-strewn spot where she was shot.

“I just think, why? Why this lady? She never argued with no one,” the man added, asking not to be named for fear of being targeted himself.

Martínez’s path into the increasingly perilous world of Mexican journalism began in the late 1980s when his journalist mother roped him into taking photos for her political magazine La Lucha de Las Féminas (Female Struggle).

Acts of aggression by perpetrator

Eglantina Esquivel said she hoped journalism would keep her teenage son off the increasingly rough streets of their border city, a longtime smuggling hub on the US border which would soon become one of the most violent places on Earth.

Martínez shared his mother’s thirst for news, although he preferred nocturnal nota roja crime reporting to politics. “It was always about getting the scoop,” Esquivel, 80, remembered at the family home overlooking Tijuana’s urban sprawl, where she has built a shrine showing her son covering someone else’s murder.

Margarito Martínez’s mother, Eglantina Esquivel. Photograph: Emilio Espejel/The Guardian

After receiving his first professional camera in the early 2000s, Martínez became an inimitable chronicler of Tijuana’s intensifying narco-battles and an icon of its tight-knit journalism community, known for his generosity and good humour.

“We felt we could save the world with our images. We felt like telling the story would wake people up to what was happening,” said Jordi Lebrija, a videographer who documented the explosion of violence alongside Martínez between 2007 and 2011.

“Nobody knew the city like him, or understood what was dangerous and what wasn’t,” said Guillermo Arias, a photojournalist who befriended Martínez after moving to Tijuana to cover the escalating drug conflict.

“He became an essential source of information and right now there’s a huge void – an information void,” Arias added. “This is the problem with the murder of journalists – it creates these vacuums.”

Martínez’s work stopped short of exploring the rampant corruption and narco politics driving so much of the bloodshed.

“He wasn’t trying to do any major investigating or exposing anybody. [At a crime scene] he’d get the details – the who, what, when, why. Maybe there was a witness he might interview … and then he would pull out and go to the next scene,” said Wendy Fry, a Tijuana-based correspondent for the San Diego Union-Tribune and friend.

Yet the murder of eight journalists so far this year – compared with seven in the whole of 2021 – has prompted a profoundly political dispute, with many accusing Mexico’s government of failing to stop the slaughter.

Some even accuse López Obrador – who has bristled at growing international condemnation of the crisis – of stoking the violence with his hostility to the media. Attacks on the press surged 85% in the first three years of Amlo’s administration, with every single Mexican state witnessing such incidents for the first time last year.

“Right now the Mexican press is caught in the crossfire between the threats and bullets of narco-traffickers and organised crime and the threats and verbal attacks and attempts to morally annihilate us from the federal and state governments,” said Adela Navarro Bello, director of the Tijuana weekly Zeta and godmother to Martínez’s daughter.

Journalist Sonia de Anda at her studio in Tijuana. Photograph: Emilio Espejel/The Guardian

“Every day [Amlo] urges society to discredit the journalistic profession – and clearly we are paying the price in blood,” said Sonia de Anda, a Tijuana journalist who confronted Amlo when he travelled there a month after Martínez’s murder in an apparent effort to calm tensions.

Amlo’s appearance had the opposite effect. After voicing regret, the 68-year-old populist began one of his trademark anti-media tirades, horrifying many grieving journalists who were present.

“They earn huge amounts of money. They are high-level mercenaries … they don’t defend the people,” Amlo said of the conservative hacks supposedly paid to malign his historic “transformation” of Mexico.

De Anda, who first encountered Amlo in the 1990s while covering his home state of Tabasco, said she was appalled by his conduct, but not surprised. “If he’s rude now, he was even worse back then … he cannot stand criticism,” she said, recalling how the then opposition leader scorned reporters he considered government stooges.

“He thinks we’re corrupt sellouts who represent certain powerful groups – and he thinks it’s best that people see us as such,” said de Anda, who thought such rhetoric – coupled with almost total impunity for those who committed crimes against journalists – was endangering lives.

Violent attacks on Mexican journalists

Martínez was not an influential media “mercenary”. In fact, he was a devoted family man who lived in Camino Verde, a hardscrabble gang-run hillside ghetto where some shacks are cobbled together from demolition timber and tarps.

Friends say he often struggled to fill the tank of his decrepit 20-year-old Dodge so he could reach crime scenes, photographs of which he was paid for by the piece.

A dog sits outside the Tijuana home of Margarito Martínez Esquivel, a few metres from where he was shot. Photograph: Emilio Espejel/The Guardian

“He worked so hard because he needed to work so hard,” said Fry. She said friends had long worried about Martínez’s safety: “His job put him in close contact to all this danger, all the time.”

Those fears sharpened last December when he was falsely accused of running Tijuana At War, a sensationalist Facebook page that unmasks cartel crooks. “That was the first time since I’d known Margarito that I could feel he was really afraid,” said Lebrija.

Spooked, Martínez inquired about being included in a government protection scheme. But before that could happen, the hitmen pounced, reportedly because they erroneously believed Martínez was behind a 14 January newspaper report about “Cabo 20” (“Corporal 20”), an infamous local mobster.

Hours after that story’s publication, Corporal 20’s henchmen began plotting the assassination, according to the Tijuana website Punto Norte. “I need a soldier for a murder,” one alleged criminal nicknamed El Huesos (Bones) told a triggerman called Uber two days later, offering him 20,000 pesos (£760) for the job.

At about the same time Eglantina Esquivel was hugging her son for the very last time. Her wrinkled face crumpling with emotion, she remembers Martínez clutching her so tightly she gasped: “Oh son, you’ll break me!”

“How could I not love you when it was I who brought you into this world?” she said as they parted.

The night before his shooting, Esquivel couldn’t sleep. She shuffled out on to her balcony to contemplate the city where her child would soon be killed. “It was as though someone was warning me what would happen. I had this sense of foreboding. My inner self could feel it.”

Esquivel said she struggled to fathom the psyche of her son’s executioners but was certain who was emboldening such killers.

“López Obrador couldn’t care less about journalists,” the bereaved mother seethed. “We have a government that’s an enemy of journalists – that is an enemy of the pen.”