The murder of Tanesha Melbourne may have been sparked by a fight in a fast food restaurant. The 17-year-old was shot and killed in a drive-by shooting yards from her home in Tottenham on Easter Monday.
But a video that was circulated on social media sites Snapchat and Twitter may have prompted what is being described as a possible "botched revenge hit".
The video shows an assault filmed inside Tinseltown Diner in Farringdon on Sunday April 1, the day before Tanesha was gunned down.
The fights shows three young men punching and kicking another male in a stairwell that leads into the diner while a young woman tries to protect the victim.
There is no suggestion that Tanesha is in the video clip or was involved in the fight in any way.
Youngsters have claimed that the fight was part of a bitter rivalry between north London gangs and that revenge for the attack caught on video may have led to the drive-by shooting.
It is understood that police investigating Tanesha's murder seized CCTV footage from the diner.
Tanesha is the 48th person murdered on London's streets this year, amid reports that the capital's murder rate now exceeds New York City's. The year threatens to be the bloodiest on record.