A stunning new twist in the story of Capa's iconic war image shows that authenticity is more than just an artistic criterion.

Federico Borrell García, a young Republican militiaman in the Spanish civil war, died, it now seems certain, on September 5 1936, shot by Francoist rebels on a hillside in Cerro Muriano near Cordoba.

His death might have gone unremarked, except that the image of that moment was celebrated for 40 years as one of the most famous war photographs of the 20th century.

It was not Borrell's name that was famous - his identity was established only relatively recently - but that of Robert Capa, whose reputation was made by the photograph.

Then, in 1975, came the suggestion that Capa had faked the picture. Now new evidence suggests another, darker twist to the story and adds a new dimension to the complex ethics of reporting war.

The first doubts were raised by journalist Phillip Knightley, in his book on media and propaganda war, The First Casualty, in which he alleged that Capa had staged the scene for the camera. Knightley discovered that the picture had first been published in the French magazine, Vu.

The caption, believed to have been written by Capa, described soldiers, "running down the slope. Suddenly their soaring was interrupted, a bullet whistled and their blood was drunk by their native soil."

A year later, Life magazine republished it, captioned as the instant of a soldier's death. Strangely, Capa had shot a picture of a second soldier, similar in appearance, falling on the identical spot; a third picture of a dead militiaman holding his rifle across his stomach corresponds to neither of the first two; and a group shot, in which Borrell is visible, is of a relaxed group posing for the camera.

None of the other images suggested a battle was in progress, though the location is known to have been on the frontline.

Capa had been vague about what happened and Knightley had tried in vain to find all the negatives to examine the sequence of events.

Capa was a great photographer but he was not averse to faking. In 1937 he fabricated footage for the March of Time newsreel series.

He told the Life photographer, Hansel Mieth, that the Borrell picture had been taken when the militiamen were fooling around, not in the heat of battle as had been believed. She added that Capa seemed upset and said little more except that it "haunted him badly".

Since Borrell's death on that day has been confirmed, the image appears to be that of the moment at which he was shot. But further evidence uncovered by the late curator of the Capa archive, Richard Wheelan - to be shown in a forthcoming exhibition at the Barbican in London - suggests another explanation for Capa's unease.

All the negatives are lost, but the contact prints and Capa's notebooks survive. Wheelan concluded that Capa and his girlfriend Gerda Taro had come across the group of militiamen taking a siesta at the foot of a slope.

The siesta was respected by both sides in the war, and since no action was taking place, Capa persuaded the men to pose for a series of simulated scenes. The contact prints of the men pointing their guns over the side of a gully, and of the group cheerfully raising their rifles for the camera appear to confirm this.

The men then climbed a hill, turned and pointed their rifles again; then, in high spirits, ran back down the hill, Capa running beside them, taking pictures. Reaching the gully, they again aimed, and perhaps fired, their rifles. The evidence from other images suggests that the fatal photograph was taken near the edge of the gully.

Significantly, a forensics expert consulted by Wheelan categorically asserts that Borrell was not running when he died. He "had been standing flat-footed when he was shot. He was clearly not in stride".

Capa's account, and the Vu caption, stated that the man had been shot as he ran down the hill.

Why should Capa have lied?

Perhaps for the same reason that he was so fortunately placed right next to Borrell, positioned to take the fatal photograph. If the militia had posed and fired for the camera, they would have attracted the attention of the rebel forces.

As Borrell stood to pose for Capa, he was cut down by a rebel bullet.

Was the secret that so tortured Capa the knowledge that without his intervention, Borrell might not have been shot?

Ever since the camera went to war, photographers have staged scenes, rearranged bodies and had events re-enacted for the camera and we look at them in two states of mind - open to their impact as authentic images, and aware that to perceive the camera as a neutral observer is naive.

Capa will always be regarded as a great photographer despite the known episodes of fakery, and many curators and critics regard this pre-digital age interrogation of the relationship between photographer and subject as irrelevant.

What matters, they argue, is the impact of the image, not what they see as spurious questions of authenticity.

But as the story of Capa's iconic photograph shows, discredited images lose their impact. If the story is not what we are invited to believe, we are entitled to resist its effects.

If Capa's actions that day did contribute to the death of Borrell, the photograph is telling a radically different and shocking story.

Truth and authenticity are not only artistic criteria. They are moral judgments too.

Below sharp, wonderfully composed, but all the wrong body language for the Death of a Loyalist, though perfect for the Death of an Actor.

Challenging The "Authenticity" of the Death of a Loyalist

The article by Isabel Hilton in the Guardian, in 2008 (reprinted in full below right) refers only to a tiny bit of the evidence and some of the experts who have challenged the authenticity of what this photograph purports to show.

By Goggling the story you can find evidence from colleagues of Capa who were there on the day the photo(s) were made. And others who recorded his comments at other times in unguarded moments.

Clearly the photo caused a sensation at the time and elevated Capa to star status as a war photographer with a single image.

What a talent, to be not only in a death defying war zone, but to actually be between the enemy and the charging, dying warrior. Why the fatal bullet must have passed between his camera straps... And to not only have the subject completely focused, and in frame, and click the shutter at the precise time a distant rifleman pressed the trigger. The mind boggles at the coincidences.

Capa, by personality, as well as for good business reasons, was not going to correct people making wrong assumptions about his talent in taking this photo and in being at the right place at the right time through sheer guts, prescience, and daredevil bravado.

He knew the photo was not the result of any of those things; it was a lucky accident that happened while he was doing what photographers have always done - fake a good shot.

No one will ever find out... It was pure Hollywood. You know, fake sincerity, fake boobs, fake morals, oh, and did we forget, the world centre of fake photography, all done with phony set-ups, and peopled with a city of actors and actresses employed solely for faking false sentiments.

So Capa clearly knew how, and why, Garcia died. And perhaps it troubled him to have propped him up, into harm's way, just for a picture.

The testimony of eyewitness contemporaries, photo analysts, terrain examiners, anatomic and behavioural specialists, and meteorological experts, combined, lead us to a few unassailable conclusions about how, and why, this photo came to be and what it depicts:

- Capa had set out to shoot some staged action pictures, not real war action photos

- the location was picked exactly because it was not dangerous at the time. It was a "quiet" part of the war zone. The soldiers who agreed to perform for Capa were picked because they had nothing else to do at the time.

- Capa had asked the men to pose running down the hill for him or pose as if falling. (One expert says body language alone shows Garcia was not running when shot, but standing, probably preparatory to doing his "death fall" for Capa who was busy focusing and setting his aperture on his Contax. When PING... and CLICK, and it was all over for Garcia and Capa had it made.

Think About It - A horse, shot at the gallop, plunges forward. A runner, with his body mass high up, and leaning ahead of his lightweight legs, if hit by a tiny bullet, will also pitch forward every time. Anyone who's ever run with a rifle, holds it way out front, not way back. It's the first thing to pitch forward when the carrier is shot. Remember, its momentum is not altered by a bullet hitting the man. It keeps on going forward, not back. And no tiny high speed bullet can countervail a body mass of 180 pound man plunging forwards.

This man is falling backwards with his legs way out in front of his body. And throwing his rifle back. As if he was hit by a huge cannon ball, or more probably a rifle bullet while standing still. That, alone, accounts for his body language and rifle position at the moment of death. He was probably shot while waiting for Capa to set the focus and exposure. In fact he falls exactly like a man standing who is shot by a firing squad.

Below the celebrated picture of Canadian Gat Howard and a colleague, supposedly being executed by the Boers. Famed illustrator George Soper shows the mechanics of how a standing body falls when shot. Note the hat falling back - like the rifle in Capa's picture.

Above another famous Boer War image by the celebrated illustrator Stanley L. Wood, showing how a man on the run really falls when he is shot - forward with his legs behind... And his hands stretched forward - and if he had a rifle it would be thrown forwards too.

This example of momentum physics would happen on flat ground. But when the runner is leaning forward, running downhill, especially on a severe slope, like in Capa's picture, the forward momentum of arms, rifle, body would be even more pronounced. Ask yourself - how can he possibly fall uphill?

Wood used behavioural common sense of bodies in motion to depict what we all know. Compare his depiction with Capa's picture of a supposed downhill runner being shot. Who's right?

- another "dying Loyalist" shows up in other Capa pictures in exactly the same place - literally - shot the same (time of) day

- Capa asked the men to do "repeats" so he could preset the focus and exposure, knowing the exact place the men were to "die" because he told them where to do it

- Garcia was killed doing a "repeat" when rebels in the area noticed what was happening on the distant hillside with men running up and down, and naturally enough, decided to go bag a victim when they weren't expecting it

- Garcia would not have died had he not done "repeats" in the same spot to please the photographer. Everyone in a war zone knows you don't repeat your behaviour lest the enemy target your predictable movements. Al Qaeda operatives in Afghanistan, Hamas leaders in Gaza, don't sleep in the same house twice. And Canadians don't drive the same route habitually in Afghanistan. They know that would be asking for it!

Perhaps Capa was not aware of these basics. The Spanish Civil War was his first war and he had only been there a short while.

He clearly was no expert at how men wage war at the time. Or was he just callous? But making a man do a repeat for a photo op - or making him stand still while Capa focused and set the aperture on his camera - in a war zone, clearly caused Garcia's death.

Blame it on Capa's inexperience if you will. Or nerve.

But without Capa's show business direction Garcia would have lived on that day.

And we would not have another in a long line of faked action war pictures.

This one unfortunately features an actor in a performance, not a soldier on the attack.

Capa has photographed wonderfully an actor whom he would never have to pay. The focus and exposure are perfect. It has all the quality of a Hollywood production still. Hey, we may be on to something there...

Do compare it with Capa's D-Day pics, eight years later, when he was in a real war zone with bullets flying all over, and Capa's pictures are shaky, poorly focused, and roughly exposed. Why the difference in real war action pictures? From the same photographer... Funny how hands get shaky when you're doing dangerous stuff... But we would definitely say that James has the steadier hand under fire...

It is every photo, TV, or movie director's dream. High priced actors doing death defying stunts so he can make a buck. And then kill them off at the end before having to issue pay checks.

This is all so far removed from the morality and ethics of Canadian war photographer, and soldier, Lt. JC Mason DSO, who asked no one to do anything dangerous, or special, for him just so he could get a great photo.

He only risked his own life, because he thought the story needed telling, not to win the fame or fortune which Capa craved.