IN the chaos that followed the Boston marathon bombings, one figure seemed to be in every image.

He was ripping down the metal railings to get to the victims, caught in the blast on the pavement. He was pushing a wheelchair, sprinting from the scene as he tried to stem the bleeding from a man who had lost his leg. He was standing deep in thought, clutching a bloodied American flag.

With his cowboy hat and long, flowing dark hair, Carlos Arredondo was easily recognisable among the confusion and the crowds.

And now he has been hailed as a hero for his attempts to save lives. "That's the first reaction: 'We have to go help somebody!'" he said.

He told The Daily Beast how his first glimpse was of a big pool of blood and several severed limbs, "with a young man in a grey top trying desperately to stand up."

As the second bomb went off 100 yards away, Mr Arredondo kept his focus on the young man, asking his name and offering his own.

"He had no legs. I told him, 'My name's Carlos, you're going to be OK, help is on the way.'"

He grabbed one of the first thing he saw that might work as a tourniquet – someone's sweater – which he ripped apart to stem the bleeding.

"That was a whole marathon," he said. "Getting people out of the way and getting him help."

But the 53-year-old Costa Rican emigrant had been through overwhelming waves of tragedy even before the terrible events of Monday afternoon.

Mr Arredondo's son Alexander was killed by a sniper in Iraq in 2004, aged 20.

When his father received the news at his Florida home, on the day of his 44th birthday, he tried to kill himself. Out of his mind with grief, he charged into his handyman's van with a can of petrol and set fire to his body – only surviving when the soldiers who came bearing the news dragged him out of the burning van.

He later apologised for his actions, but abandoned his trade to tour the country full time as a peace activist, speaking out across the war from his ornately-decorated camper van.

Until that moment, Mr Arredondo had in many ways embodied the "American Dream" – something he himself admitted in an interview.

He was born on the outskirts of the Costa Rican capital, San Jose. In search of work he crossed into Nicaragua, but found himself caught up in the civil war between the Sandinistas and Contras. He was detained several times, and eventually, in 1980, decided to make the dangerous journey through Central America and across the Mexican border to the United States.

Accompanied by a Costa Rican friend and two Guatemalans, they trekked through the desert, baking during the day and freezing during the night – all the time fearing for their lives from the violent people traffickers known as "Coyotes".

Mr Arredondo made his way to Long Beach in California, where he initially lived rough beneath a bridge. He found work in a sandwich factory, but it was not enough to survive on. After three months he and his friend decided to hitch hike to Boston, where he eventually met his first wife, Victoria Foley, and settled, fathering two sons.

"It was the American Dream for me, to have my sons in the United States, born healthy and well. The promise of education and health seduced us; we wanted a better life for our families.

"As a Costa Rican, then living in Nicaragua, we saw so many people dying. We wanted a peaceful existence."

Then his eldest son signed up to the Marines, lured with the promise of an education and a lump cash sum for his family.

"I told my son I support you, but I'm afraid – I don't want you to come back in a body bag," Mr Arredondo said in an interview in 2006.

"Alexander said 'Dad, don't worry – we're not at war.' Because in 2004 the war in Iraq was fairly localised, it wasn't affecting everyone. So off he went."

Alexander's death had a devastating impact on the family. In December 2011 Mr Arredondo's second son Brian, then 24, committed suicide after becoming severely depressed and spiralling into drug addiction following the loss of his brother.

But it did not stop Mr Arredondo's campaign. Having become an American citizen in 2006, he moved from Florida back to Boston with his second wife Melida and volunteered for the Red Cross, as well as continuing his peace activism.

It was for this that he was at the Boston marathon, wearing badges of his son's faces pinned to his own grey sweatshirt.

By Harriet Alexander, Telegraph.co.uk

Online Editors