In 2008 Alex Vanderpuye was jailed for six years after being convicted of the rape and false imprisonment of the 14-year-old girl.
Nine years later Vanderpuye was stabbed to death in the street.
Three men were arrested but as yet nobody has been charged with his murder of December 7.
"Hackney is a busy and vibrant borough and this incident took place at a time where lots of people would have been around. No matter how insignificant you think it may be, please make the call," said Detective Chief Inspector Jamie Piscopo, who is leading the investigation.
Detective Chief Inspector Piscopo said he would not comment on Mr. Vanderpuye's criminal record and said it was "not a specific line of enquiry" and he was keeping an "open mind".
Terrifying Reign of Kingzhold Boys
In April 2007 Vanderpuye was one of nine boys who overpowered the girl in a street in Hackney.
They were known as the Kingzhold Boys — their name was derived from the former Kingshold estate which was demolished in 1990 — and they were led by O'Neil Denton, a 14-year-old who was more than six feet tall and had the streetname of "Hitman".
The gang ruled the Frampton Park estate in Hackney and the girl had upset gang leader Denton with comments she had made to his girlfriend.
The gang rape was her punishment and her ordeal would last two hours.
Denton and Vanderpuye, were joined by 15-year-old Jayden Ryan, who weighed 238 pounds, and six other boys.
Girl's Horrifying Ordeal
The victim was frogmarched to three different locations on and was stripped, raped, punched, kicked and had her head bashed against a wall.
She was forced to dress between each attack before being spat on and dumped in the stairwell of a tower block on the Frampton Park estate.
"One of the gang pulled out a knife and told me if I didn't do what they wanted, they would stab me up. They were surrounding me, laughing and whooping. There were so many grabbing at me, pulling my clothes off. I'd reached the point of giving up. I really thought I was going to die," the girl told police.
She begged them to leave her alone and wept throughout her ordeal.
"Better cry because I am only going to give you something to cry about," Denton told her.
Victim and Her Family Went Into Hiding
When the girl went to the police and agreed to testify against the gang she had to be moved out of the area, along with her mother and stepfather, and other witnesses had panic buttons installed in their homes.
Denton and another boy, Weiled Ibrahim, 17, were given an indefinite term of detention for public protection at Snaresbrook Crown Court in 2008.
"You had power over the others. Your pre-sentence report points to motives of revenge, sexual gratification and exercising a power over both your victim and your gang," Judge Wendy Joseph QC told Denton.
At the same hearing the court heard the victim was suffering from post-traumatic stress disorder and had begun self-harming.
She is protected by an anonymity order, but it is almost certain she is still suffering from her ordeal at the hands of Vanderpuye and his friends.
Vanderpuye is thought to have drifted back into crime after his release from a young offenders' institution and it is possible he was murdered because of a dispute over drugs or because of a gang affiliation.
The Frampton Park estate has largely been demolished and redeveloped since 2007.