The video he gives me makes me sick, sad, worried and excited.

It is filmed from the inside of a group of assassins—or sicarios—carrying out a hit, which in Mexican newspeak is called an execution. The image is grainy and pixelated, almost certainly filmed from a cell phone. The author swings the cell phone camera wildly, signaling he is pumped full of adrenalin. He points it to a sicario in his early twenties, dressed in jeans and sneakers, holding up a Kalashnikov rifle and squeezing the trigger so it shakes hard against his shoulder. He points the camera to an older sicario, who wears a baseball cap and black uniform, and fires with an AR-15, the “civilian” version of the M16 that American troops have used from Vietnam to Afghanistan. And he points the camera to the victim, his body bouncing with the bullet impacts, blood jetting out like water as he collapses on the sidewalk.

What am I going to do with this? The film shows the action that we journalists miss as we try and document Mexico’s relentless narco violence. We always arrive at the scenes after the “executions” and film death. When documentary makers paint films about Mexico’s narco conflict, they have footage of thousands upon thousands of corpses to choose from, but no fighting. We can’t embed with the combatants, like journalists embed with U.S. troops in Iraq or even rebels in Syria. Iconic photographs of Afghanistan show grimacing soldiers in the midst of firefights. In the most commended shots of Mexico’s violence, photographers portray bodies, albeit using their skills to show them beautifully. Should I put this execution video into the documentaries and news pieces that I make? Does it have a journalistic value in helping decipher this bloodshed?

But there are grave ethical problems with using it. Can you allow somebody involved with a gang of assassins to be your photographer? Would you be acting as a vehicle for their propaganda of violence, helping spread terror? Can you adequately verify the authenticity of the video? And what about the victim? Is this grossly unfair on him and his family to show his murder on a news program?

The most decisive factor is security. I don’t think you can make out the faces of the sicarios. But what if someone can? Would it be used as part of an arrest or prosecution? Will it lead to a revenge hit? Could I make somebody very angry? And for this reason, I decide the video is best left off the ten o clock news.

Covering Mexico’s narco bloodshed, journalists grapple with such internal questions day after day. Gangsters leave piles of decapitated heads in city squares. They print messages on blankets, making serious accusations against politicians. They give the media videos of thugs torturing and murdering men who are tied to chairs in dark rooms. What are the guidelines for covering this? What is the balance between informing the world of a tragic but important historical upheaval, acting as a mouthpiece for mass murderers, and protecting the journalists? What does freedom of speech best mean in this context?

These journalistic dilemmas underline the central features of Mexico’s drug war that everyone struggles to make sense of. It is an atypical armed conflict. There has not been another low intensity war quite like this before in another country—although maybe more will come. Narco gunmen attack like guerillas using rocket-propelled grenades and belt driven machine guns yet do not possess an ideology. Cartels fight over territory yet they are still clandestine, acting as ominous shadow powers. The government denies there is an armed conflict, saying it is a purely criminal problem, and yet soldiers shoot dead more than 2,000 people over five years—according to their own numbers. And a primitively brutal violence plays out through the high tech media of cell phone videos, YouTube and Twitter.

Journalists who live in the frontline states, where the violence is most intense, make their coverage choices in extremely stressful conditions. In Michoacán, Chihuahua, Nuevo Leon, Tamaulipas, Guerrero, Sinaloa, Durango, Veracruz and others, they know the wrong decision could bring gangsters firing rifles and grenades at their offices, or breaking into their homes and dragging them into the darkness. The murder of dozens of media workers in recent years looms and each new case reinforces terror. This body count of journalists is tragically the central story on freedom of speech in Mexico.

The bloodshed has left black holes in parts of the country, where journalists have fled or been beaten into self-censorship. A car bomb went off in Nuevo Laredo last June, minutes from the U.S. border, sending seven bystanders to hospital. We had no video or photos for the news bulletins because most media outlets are too scared to cover violence in the city. In today’s world where every event is archived on film, a lack of video gives an atrocity like this less attention. We start to wonder if the event really happened in our TV-guided reality. Victims living their lives with burn scars over their faces know otherwise.

But despite these no mans lands, we should also recognize the overall bravery and resilience of Mexico’s regional journalists who keep on covering this conflict, despite the systematic attack on them. They soldier on providing footage of shoot outs in the Tierra Caliente of Michoacán, photos of the forty nine decapitated bodies or a road near Monterrey, interviews with poor crying mothers trekking to San Fernando to see if a body hauled from a pit is their lost son. Myself and others who have written books and made documentaries about this narco war could never have done our jobs without the help of local journalists reporting year after year on the tragic conflict in their communities. I am always impressed by their drive and generosity in sharing both their knowledge and friendship. While war is packed with stories of villains, it also contains stories of bravery and compassion.

I first arrived in Mexico from Britain in the year 2000, the day before President Vicente Fox took power, ending seven decades of one party rule by the Institutional Revolutionary Party or PRI. In the American and British media, we portrayed it as a time of optimism and hope, of a market-friendly democratic president who could bring Mexico into the twenty first century, with all the rights of modern states such as freedom of speech. But as the decade progressed, this freedom was threatened by a new force—the death squads of cartels, financed by billions of dollars in drug profits from American users. The government was less able to buy off and coerce the media, but journalists were increasingly attacked by gangsters.

I followed Mexican crime-beat reporters in cities such as Nuevo Laredo, over the Rio Grande from Laredo, Texas, which was one of the first places to suffer from this new type of urban warfare. Mexican journalists call this beat “la nota roja,” which literally means “the red news.” They were extremely skilled at finding out when there had been a murder by scanning police radios or from an array of contacts and then burning rubber to get to the crime scenes before they were blocked off. We would get calls as we were in the middle of dinner and rush out of restaurants to blaze past red lights with our adrenalin pumping and arrive to see another twisted body on the concrete, another devastated wife weeping.

This grunt work by journalists documenting murders up and down the country exposed the scale of the emerging conflict. National newspapers and TV stations would tally up all the reports of the cartel related homicides and release counts, known by the (rather sick) term execution meters. In 2004, they found more than 1,000 such killings. By 2011, this had risen to more than 12,000 cases in a single year. The numbers produced by the press were staggering, bringing international attention to the violence.

The first torture and murder video I can remember came in late 2005. It shows a man tied to a chair begging for his life and confessing to various crimes including the killing of a radio journalist in Nuevo Laredo. It appeared to be a rival cartel torturing him and from what they are saying it was filmed in Acapulco. (Bizarrely, the video was sent anonymously to a regional newspaper in the northwest United States.) At the end of the film, a hand appears with a gun and shoots the man in the head.

The following year, cartel assassins first began to decapitate victims. Two heads of policemen were left on a wall in Acapulco. Then thugs rolled five severed braincases onto a disco dance floor in Michoacán, an atrocity that finally grabbed global headlines. A video of the scene is haunting. The faces look eerily calm, their muscles no longer flexed as life has drained from them. But looking down you see the horror of hacked up necks bathing in pools of blood. While the atrocity shocked people, it also inspired other cartels to follow and soon it seemed every squad of killers in Mexico had an executioner’s axe in its arsenal. Last year alone saw more than 500 decapitations.

There is heated discussion as to why Mexican assassins took to beheading. Some say they were inspired by the videos of Al Qaeda, with film of the May 2004 decapitation of a U.S. businessman in Iraq shown on some Mexican TV channels. Others say that Guatemalan mercenaries introduced the technique. Members of the elite Kaibil force had cut the heads off leftist rebels to terrorize villages during Guatemala’s brutal civil war; deserting the military, they sold their skills to Mexican mobsters - turning anti-insurgency tactics into cartel terror tactics. Others point to the historic use of beheading in Mexico from the human sacrifices by the Aztecs to the Spanish colonists publicly displaying the heads of independence leaders.

Whatever the reasons, cartels increasingly turned their violence into acts of public propaganda. This only intensified when President Felipe Calderon took power in 2006 and declared a military offensive against drug traffickers, leading to a sharp escalation of violence. Policemen were murdered and their bodies dressed in comic sombreros; a human face was sewn onto a soccer ball; assassins made videos of twelve decapitated victims; then eighteen; and then forty-nine. It was like rival cartels were playing high stakes poker and kept raising the bets to try and buy the pot. No one could back down.

The media struggled to know how to cover it. After first giving atrocities front-page attention, they questioned whether they were playing into the hands of gangsters. One suspected gunmen, who was arrested for setting off a car bomb, said they deliberately planned attacks to coincide with TV news bulletins. But journalists were under pressure from all sides. Editors received calls from thugs making sure they covered specific massacres and others warning them not to cover certain events or use certain names. When gunmen killed a young photographer from the Diario de Juarez on his lunch break in 2010, the newspaper released a landmark editorial addressed to the cartels, entitled “What do you want from us.”

“You are at this time the de facto authorities in this city because the legal authorities have not been able to stop our colleagues from falling, despite the fact that we’ve repeatedly demanded it from them,” the editorial said. “Even war has rules. In any outbreak of conflict, protocols or guarantees exist for the groups in conflict, in order to safeguard the integrity of the journalists who cover it. This is why we reiterate, gentleman of the various narco-trafficking organizations, that you explain what it is you want from us so we don’t have to pay tribute with the lives of our colleagues.”

The Calderon administration reacted angrily to the editorial. Meanwhile, the security forces made their own efforts to fight the propaganda war. Suspects detained by police or soldiers were made to confess in front of TV cameras. In one case, a fourteen old boy held by soldiers told journalists he had decapitated four people. Other suspects were shown in interrogation videos, detailing their lives as mass murderers and how they killed hundreds - accounts that played on prime time news shows. In 2009, Mexican marines shot dead arch gangster Arturo Beltran Leyva, alias “The Beard,” in the spa city of Cuernavaca. When journalists arrived to photograph his body, Beltran’s trousers had been pulled down to his ankles and dollar bills decorated his corpse. It was another example of the propaganda of violence.

In 2011, the Calderon government led hundreds of media outlets to sign a national pact aimed to regulate media coverage of Mexico’s drug war. The first point was, “not to be spokesmen for organized crime” and it also advocated not “interfering” with crime fighting. However, several major newspapers and magazines refused to support the pact, arguing it was an attempt to censor the press. The government was just trying to make the narco war go away, they said, by limiting coverage of it. Some Mexican government officials have certainly shown this point of view in my discussions with them, betraying the view that narco violence is primarily a problem of Mexico’s image in the world – rather than of the victims.

But while the pact itself was largely forgotten, media coverage of the narco war has diminished in the last year, with spectacular acts of violence getting less room on news shows and narco videos ignored. This is partly due to editors not wanting to spread cartel propaganda and partly to a tiny decline in the body count (which is still outrageously high). But it is also because of oversaturation. People are no longer shocked by piles of heads in Mexico. There have been too many.

In 2012, the PRI returned to power under President Enrique Peña Nieto, thanks to some extent to voters believing the old guard could restore order. Maybe, elections were rigged in much of the twentieth century, people said, but at least you didn’t have psychopaths with RPGs digging mass graves for hundreds of victims. Peña Nieto promises that the PRI is an overhauled democratic party that will never again control the press like its governments did back in the 1970s. Time will tell if this is true – and how much Mexicans will be prepared to sacrifice certain freedoms if they believe it will bring them more security.

The world needs to pay attention to how this plays out. Mexico is important not just because of the morbid fascination with severed heads on internet videos, but because this new type of conflict could play out in many other countries. Criminal groups with military grade weapons, weak and corrupt governments, and organized crime dominating chunks of the economy are threats across the globe. A central issue in the twenty first century is how we can guarantee our security from these challenges, and still defend our freedoms.