When Hashim Garrett was 15, he was shot on a Brooklyn street. Six sub-machine gun bullets fired by another gang member tore through his body and out the other side.
Now 33, the New Yorker, who was left paralysed from the waist down, has been talking to the Department for Children, Schools and Families about how to stop the spread of gang violence in the UK.
The department recently told teachers to seek advice before inviting former gang members into schools in case it promoted their lifestyles. But Mr Garrett's own experiences were far from glamorous. In 1990, he was left bleeding on the ground, "scared out of my mind", and had an out-of-body experience.
"But I wasn't heading towards that light in the sky that most people describe," he said. "I was heading somewhere dark."
He said he noticed signs of the spread of gang culture to London schools when he visited earlier this year. "The main difference is that in America we use guns and in England knives are more prevalent," he said. "But all the factors that play a role in why young people hurt each other are exactly the same."
His recent visits to British schools were organised by Breaking the Cycle, a US charity which began operating in the UK in January. It offers assemblies to schools: speakers include former gang members from the US and Brixton.
Hans Voll, one of its officials, said its visits to secondaries were booked up until November, and it had been asked into primaries too. "Teachers are desperate to do something," he said.
"Too many kids live in fear, but just need someone to talk to."
Breaking the Cycle is funded by a Christian charity, but Mr Voll said its message - that pupils should avoid conflict through forgiveness - was not religious but universal.
Mr Garrett, who is a Muslim, tells pupils how he chose not to seek revenge on his attacker or press charges. He later found it was his own gang - older youths he had tried to impress - that set him up. "I tell students that gang members will love you and take care of you, but only up to a point," he said.
His advice to teachers is be pro-active. "Don't wait until there is a fight in a school before you talk about conflict resolution," he said.
And he praised British ministers and schools for taking the threat seriously, but he fears Britain may already be on the same road as the US, where publicity helped two Los Angeles gangs to spread nationally. "I wouldn't be surprised if in five years you have the Crips and the Bloods over there in London, or some version of them," he said.