A 16-year-old stabbed to death in west London had been interviewed on television days earlier saying the danger of knife crime was exaggerated.
Kodjo Yenga, of Portland Road, Notting Hill, was chased, beaten and stabbed through the heart on Wednesday.
Five days earlier he told an MTV programme: "Stabbings are getting worse but the media is also making it bigger than what it is."
Nine people, aged 13 to 21, have been arrested in connection with his death.
Those questioned by police include two teenage boys, aged 14 and 16, arrested at their west London homes on Friday morning.
Kodjo was an interviewee in a programme about knife crime and was asked about its prevalence.
He said: "I don't think it happens all the time but it happens quite a lot."
People have left tributes on a wall and flowers near the scene
Teachers and friends paid tribute to Kodjo on Friday, with flowers and candles left at a makeshift shrine near the row of shops where he was stabbed.
Messages posted on Kodjo's personal web page said that he would be "dearly missed" and would "never be forgotten".
Paul O'Shea, principal of St Charles Catholic Sixth Form College where Kodjo was a student, called him "a friendly, gentle and peaceful young man".
According to Mr O'Shea, Kodjo was "an able student... who was regarded with great affection by his fellow students and his teachers".
"He was a credit to his mother and wider family, to whom all the students and staff at St Charles College offer their heart-felt condolences."
Those sentiments have been echoed by users of the Bebo website, on which Kodjo had a web page under the nickname Kizzle Sweet-thug.
"I love u bruva," reads one posting, while another describes him as a "fallen soulja" who was "loved dearly".
Det Ch Insp Tony Nash said: "We are talking about the senseless taking of a 16-year-old boy's life. This is a meaningless crime and a despicable crime.
"We are looking at a nightmare come true for one young man and his family and friends."
The officer said Kodjo was walking in Hammersmith Grove with his girlfriend when he was approached by a large group of youths.
"He was then chased, caught, beaten and stabbed," Det Ch Insp Nash said.