IF there is one harsh lesson learned by all those connected to the killing of 18-year-old Sean Nolan, it is that a few seconds can be enough to end one life and destroy others.

For his killer Finn Colclough, convicted of manslaughter by a jury at the Central Criminal Court, it's a lesson he will no doubt never forget.

For Sean, a young man with the world at his feet, and for then 17-year-old Colclough, Friday, May 25, 2007, was always destined to be a red-letter day.

On that fateful day, Sean walked out of his final class as a sixth-year student in St Joseph's CBS, in Fairview. Only the Leaving Cert exams stood between him and the beginning of the next chapter in his life.

Across the city in the Institute of Education on Leeson Street, fifth-year student Colclough was celebrating the final day of term.

Having waved goodbye to his school days, Sean joined parents Charlotte and Michael and classmates for a special graduation Mass in the school.

Later, after tea and biscuits, the young men continued the party with a number of teachers, visiting several pubs and clubs.

Over on the south side, Colclough was dressed up to the nines as he attended a 21st birthday party in Spy nightclub.

The teenager suffered from severe OCD and had a number of speech and language problems. But these didn't affect his friendships and he was surrounded by a group of pals.

With a free bar during the early part of the evening, Colcough and his friends had several glasses of wine and cocktails. By 2.30am, they were back in the Colclough family home on Waterloo Road where his parents Alix and John were asleep upstairs. The gang chatted happily in the basement kitchen while making sandwiches. According to his pals, Colclough was "very drunk". He shared a marijuana joint with one friend.

By 4am, most of the revellers had retired to bed. Colclough wasn't tired, so he and two young pals decided to take a walk. What happened next depends on which version one is inclined to believe: Sean and his two friends Eric Treacy and Ciaran Wogan were wandering along Waterloo Road, holding a bottle of wine and looking for the house of a girl called Sara.

corkscrew

When they bumped into Colclough and his two friends, they asked for directions. Sean's pals would later testify in court that the exchange between the two groups was "friendly enough".

Colclough's friends described the short meeting as peppered with foul language and aggression. Having returned home, Colclough was in the kitchen when he noticed the trio of young men loitering outside. They were waving a bottle of wine, apparently looking for a corkscrew.

He would later explain to gardai that he felt "frightened" by the group, so he locked the door.

He then grabbed two knives and ran outside, shouting and waving in what he called an attempt to "frighten them off".

Sean wasn't about to be intimidated into leaving, squaring up to Colclough and his knives. A punch was thrown, one man pushed the other, hands flailed and it was all over.

Sean stepped back, looked at his shirt and said: "you stabbed me, you f****ng stabbed me".

Colclough saw no blood. He later claimed to gardai that he'd assumed he had merely scratched the other man so he continued shouting at him.

He insisted that it was only when he returned to the kitchen that he saw blood on the knife. Acting fast, he quickly washed the blood in the kitchen sink.

By now, the single fatal wound to Sean's chest was already seeping blood. Colclough then returned outside, looked at the group, and ran back to the kitchen where he phoned for an ambulance. It was now 4.11am. Within minutes, fire service personnel were on the scene and a gravely ill Sean was rushed to St Vincent's hospital where A&E staff had been alerted.

Meanwhile, gardai were entering the house at 71 Waterloo Road. One witness had described the culprit as a plump man, with long hair. When he saw gardai entering, Colclough immediately said: "It was me."

It was 4.30am when he arrived at Donnybrook station. A short drive away, doctors were frantically working to save Sean's life. At 4.40am, they gave up their futile battle and pronounced the victim dead.

As this heartbreaking scenario played out, two sets of parents were rushing to diff-erent locations in Dublin 4 -- one to hear that their son had died, the other to discover the first chapter in their own nightmare.

On both sides of the Liffey, teenagers found themselves forced to grow up far too fast.