The matrix, which is secret, allows the police to keep track of who is in what gang and what the current "beefs" are between rivals.
"It really can save lives," said Commander Jim Stokley, who leads the Met's response on gang crime.
"This year violent crime, and its fatal consequences, has often been in the headlines for very real and sadly obvious reasons. The statistics speak for themselves — 11 young men aged 25 and under have been murdered so far in 2018. But those statistics represent young people — much loved sons, brothers, friends. We must never forget the human tragedy and cost," said Cmdr. Stokley.
He said half of all gun crime in the capital and one in five knife attacks was linked to gangs.
Why So Many Black People on the Matrix?
But the matrix has been criticized by groups, including the Institute for Race Relations, because of the ethnic composition of those on the database.
In 2015 Lee Bridges, a law professor from the University of Warwick, analyzed the database and found78.2 percent of the 3,422 people on it were black, compared with only 8.7 percent white people.
He said it was "remarkable" for the Met to claim only 439 white people in London were engaged in "violence, criminal offending and gang membership."
Labour MP David Lammy also criticized the gang matrix in his review of the relationship between black people and the criminal justice system, which was carried out last year for the government.
BAME Youths 'Over-Represented' on the Matrix
Patrick Williams, senior lecturer in criminology at Manchester Metropolitan University, published an article in 2016 pointing out that while 87 percent of those on London's gang matrix were Black and Minority Ethnic (BAME), they accounted for only 50 percent of those convicted of youth violence.
In Manchester the figures are even starker — 89 percent of those on Greater Manchester Police's Xcalibre gang database were BAME but only 23 percent of convictions for youth violence were people of BAME origin.
The Mayor's Office for Policing and Crime are doing a review of the gang matrix but the Met is sticking to its guns and insists it is both fair and useful.
"The gang violence matrix is an intelligence tool that the Met uses to understand the threat of violence posed by gangs and also importantly to gang members," said Cmdr. Stokley.
"We build a picture based on intelligence — from police, our partner agencies, and from Londoners — our communities. The matrix is then used to target activity to reduce the risks of violence posed by or threatened against our young people. That can be any number of things from diversion schemes, including help with employment, to enforcement activity," he said.
Matrix Was Set Up After 2011 London Riots
The matrix was set up in 2011 in the aftermath of the London riots when the Met realized it had lost track of who was in gangs and which areas those gangs considered their home turf.
The trigger for those riots was the shooting of Mark Duggan, an unarmed black man who was a leading member of the Tottenham Man Dem (TMD) gang.
The gangs now on the matrix including the TMD in north London, Murder Dem Pussies (MDP) in west London, Don't Say Nothing (DSN) in south London and east London's Hoxton Boys, Fellows Court and London Fields gangs.
Some London councils, like Croydon, have also invested heavily in anti-gang strategies but it is the police who are most focused on gangs.
'Strict Criteria For Being Included'
"We have invested a lot of time in understanding who is likely to be a victim, or aggressor, or both. We use a very strict criteria — the threshold for including a person on the matrix is high. Only where we have at least two corroborated pieces of tested intelligence are people included. Inclusion is kept under constant review and whilst about 3,500 people are currently included, since 2012 over 4,000 people have been removed," said Cmdr. Stokley.
Those 4,000 include gang members who have been killed, deported or incarcerated but it also includes those who have been "diverted from crime" and have left the gang lifestyle behind.
"The Met is determined that we will play our part in making sure our young people know they have choices, they can get support to turn away from gangs, that our intelligence is for their protection from harm as equally as it is for enforcement. What we want is to do all we can to stop young people from joining a gang in the first place. Londoners can help us — we all have a part to play. If you know of a youngster at risk of being drawn into a gang, or who is already part of one, please tell us," said Cmdr. Stokley.
Amnesty International told Sputnik they could not comment on Cmdr. Stokley's comments but would be publishing a report later this year about the gang matrix.