The parents of a student who was knifed to death after remonstrating with youths who threw conkers at him told today of their grief.
Steven Grisales, 21, was attacked as he made his way to Silver Street railway station in Edmonton, north London last Wednesday.
He died the next day from a single stab wound to the heart.
A 15-year-old boy has been charged with his murder and appeared in court today.
Speaking from the scene, his mother Jasmid wept as her husband Andres told of their heartbreak.
Mr Grisales said his son was a "great boy" whose brothers and sisters were "devastated" by his death.
The couple appeared near the murder scene in College Close to pay tribute to their eldest child and appeal for witnesses to come forward.
Mr Grisales, who was in Argentina on business when his son was killed, said Steven had been visiting his grandmother and shopping for her before he was attacked.
He said he had done nothing wrong in the run-up to the stabbing.
"He did everything right," he said.
"It wasn't that he stayed late.
"It wasn't that it was late at night.
"He didn't drink, he didn't smoke, he wasn't into any gangs or any large groups.
"His friends and cousin were all professionals, had all finished university."
Hugging his inconsolable wife to him he said such attacks do not occur in Argentina, where he works, and Colombia, where the family are from.
He said: "It's incredible that this would happen to him.
"It is devastating for all of us, the whole family, aunties, cousins, grandma, uncles, back home, it's been horrible because we don't get it.
"We don't understand.
"Without a reason, without nothing."
Mrs Grisales received a call from police on her son's mobile phone shortly after the stabbing. She went to the hospital and his father flew home.
Mrs Grisales saw Steven before he died, her husband said.
"She was with him all the time, next to him," said Mr Grisales, stopping to support his wife who had broken down.
He went on: "Steven was a great boy, very responsible, he was really family orientated." ]
The victim, from Enfield, north London, had returned from Argentina, where he was helping his father, on August 5.
He was excited about returning to Britain and embarking on a three-year architecture course as part of a scholarship from Westminster College.
"He was so happy getting back," his father said.
The victim leaves two sisters, aged six and 11, and a brother aged two.
Mr Grisales said the eldest daughter was "devastated, she's been crying and can't sleep" and said he could not explain how he felt about those responsible for Steven's death.
He applauded the police for their help and urged witnesses to help them.
He said: "Please come forward. If you've seen something or the person who did it, if you saw the incident or what happened or what happened around it, you have to come forward to help with the investigation.
"This is really hard, it shouldn't happen to anyone, but it did."
Detective Inspector Richard Beadle said the "unnecessary" conker attack "deteriorated quite quickly" and resulted in the murder.
He appealed for witnesses to come forward and said the victim was involved in an incident "not of his own making".
He said: "Quite a lot of people have seen that, quite a lot of people have seen what happened and we need to find out exactly who did what, who said what and exactly what that involvement was ... I desperately need those people that saw what happened to come and speak to us because Steven has lost his life totally unnecessarily."
Referring to the conker attack, Mr Beadle said: "It is really, really upsetting for everybody that something so trivial can result in a young man losing his life.
"It's an indication of how sad, how horrific it is that so many people are not only carrying knives in London but are actually prepared to use them."
Mr Beadle, whose officers will return to the scene tonight one week on to jog people's memories, said there had already been "tremendous assistance" from some witnesses.
Victoria Atta-Saow, 56, saw the aftermath of the stabbing which happened outside her house.
She said it took the ambulance 27 minutes to arrive and a boy summoned a passing police car from the main road into College Close.
"We heard a dog barking outside and thought there was a dog fight.
"My daughter ran outside and I followed and we saw the man lying down in the arms of the lady next door. The lady said he told her the group had thrown conkers at him so he'd thrown one back.
"He told her he was stabbed and asked her to call an ambulance. Everybody tried to do what they could.
"It took 27 minutes for it (the ambulance) to arrive. A small boy ran down to the main road and flagged a police car to come in.
"We didn't see any of the guys who did it."
The 15-year-old charged with murder appeared before magistrates in Enfield this morning and will appear at the Old Bailey tomorrow.
Four other teenagers were arrested and released on bail. They were two males aged 15 and 19 and two girls aged 15 and 16.
Floral tributes appeared today.
One read: "Steven - a young man with a smile like sunshine - it could light up a room. RIP. Marie."
Two other messages on the same bouquet said "Stevo. You will live long in all of our hearts. I miss you very much. RIP. PJ", and "Steve I can't say how much I miss you. I wish you didn't have to go. You will always be in our hearts. Gone but never forgotten. RIP. Courtney."
An A4-sized photo montage of the victim was also left among the tributes next to a porcelain cherub and a blue tie.