RIO DE JANEIRO • At first glance, what unites Brad Snyder and Sebastian Rodriguez Veloso is more obvious than what divides them.
As Paralympic swimmers, they share a sport, and a struggle.
They both have a past scarred by trauma and the extraordinary fortitude that has enabled them to overcome it.
Snyder lost his sight in an explosion while serving as a bomb-disposal expert with the US Navy in Afghanistan.
It was a bomb too, that ultimately cost Rodriguez the use of his legs.
Here, though, is where their stories diverge, because Rodriguez was not the victim, he was the bomber.
As a young man, Rodriguez - who finished fifth in the S5 200m freestyle final on Friday - was a member of Grapo, a Spanish republican terrorist group.
He carried out several bomb attacks and the murder of an Andalusian businessman. In 1984, at the age of 26, he was sentenced to 84 years in jail.
"At the time, I was young and that seemed to me a way to fight for a better world," he told Portuguese newspaper Record last year. "It was only later that I realised I had chosen the wrong path."
While in jail, Rodriguez went on hunger strike for 432 days, permanently damaging his health and leaving him without the use of his legs.
In 1994, he was freed under a Spanish law granting parole to seriously ill inmates. In 2000, he competed at his first Paralympic Games, winning five golds.
At 59, Rodriguez is reaching the end of his sporting career, but he remains a figure of inescapable fascination, particularly as the number of his fellow competitors who owe their injuries to bombs has swelled.
One consequence of the shifting geopolitical landscape since the millennium has been that an ever-growing proportion of Paralympians are ex-military personnel maimed by insurgent attacks.
Among that number is Snyder, a double gold medallist at London 2012 , who is defending his titles in the S11 100m and 400m freestyle in Rio, while targeting a further three golds.
Like Rodriguez, his path to the Paralympic pool was shaped by terrorism.
"I was a kid in high school when the towers came down in New York (during the 9/11 attacks) and a lot of my life was dedicated to the idea of protecting (people) from terrorism," he explains.
"My goal as a service member of the United States was to defend the concept of freedom. I volunteered to serve knowing the risks that I was taking, and I would do it again in a heartbeat.
"And I look at my new role in the Paralympic movement as promoting goodwill between all the countries in the world. I still feel strongly that I want to contribute to a world that is terrorism-free."
Snyder was not aware that he had been sharing a pool with a man who once supported the ideology that robbed him of his sight until he was contacted for this piece.
Yet his instinctive reaction was one of compassion and forgiveness.
"I'm certainly not uncomfortable (to share a pool with him)," he said. "I don't know that he and I are going to be best friends any time soon but I've always tried to empathise with everybody else."
Rodriguez does not like to address his terrorist past directly but has expressed remorse for his crimes.
"I cannot deny my past," he told Record. "I can never erase the crime I committed. It is part of my life. But my life is not just that. Today I see that violence does not lead anywhere."
The issue of whether the sporting arena should be accessible to those who have committed a serious crime is a complex and polarising one, and there are no easy answers.
Many in Spain are uneasy at the integration of Rodriguez into their Paralympic team - a process smoothed by a royal pardon from King Juan Carlos in 2007.
Rodriguez knows that he will never escape the words of condemnation and disgust. But when he dives into the pool, the stigma of his past is washed away.
"In the water, there are no obstacles," he says. "I am like you. I am free."
THE TIMES, LONDON