A photograph that shows Irishman Martin Kelledy finishing the Boston Marathon - with one of the two men who allegedly bombed the race clearly pictured behind him - startled the Irish runner when it was published this week.

The new photograph shows alleged bomber Dzhokhar Tsarnaev, 19, captured in the background behind Kelledy just moments before the two suspects separated to detonate their bombs.

Kelledy told The Star this week he still gets the shivers every time he looks at the photograph, more than a week on from the shocking attack.

'It creeps me out looking at it,' said Martin, of Dundalk, County Louth. The photo was reportedly taken just as the Irish electrician crossed the finish line of the race.

Minutes later the bomb that Tsarnaev left in a rucksack went off, killing three people.

Dzhokhar, currently under armed guard in hospital, wears the distinctive white cap that helped cops and FBI personnel quickly track him down.

His brother Tamerlan, who died after a shootout with police in Boston last Thursday, is pictured to the right of his brother and his own distinctive black-and-white cap is just visible in the crowd.

Moments after the picture was taken, Kelledy finished the marathon in three hours and 50 minutes. The first bomb exploded about seven minutes after he crossed the line, while he was talking with two friends.

'I did not have a clue that it was a bomb,' Martin said from his home in south Boston. 'I thought it was a gas explosion or something, but then 10 seconds later the second bomb went off and I knew then.'

Martin said he was instantly concerned about his girlfriend of six years Jennifer Sax, who was in the stand close to where the first bomb went off.

'I was really worried for Jennifer and her dad and was frantically looking for her. I had no phone with me and thankfully we had already agreed a meeting point at a pub. I got there just two minutes before she arrived and it was a great relief to see her.'

The photo emerged a few days after the tragedy — and quickly went viral when people realised the bombers were in the background.

'The last mile of the marathon was the fastest one for me. I keep thinking that if I had been slower I could have been caught up in it. It is a terrible thing to think about.'