The rise and fall of Brixton's GAS gang
Many people will know about the crimes of the GAS gang - based in Brixton, south London - but fewer know of the gang's history, writes the Today programme's Andrew Hosken.
At least six killings have been linked to GAS in recent years and, in the last 12 months alone, eight suspected members have been jailed for murder or attempted murder.
Earlier this year, three GAS members were jailed for life for one of the worst gang-related crimes in recent years.
Nathaniel Grant, Kazeem Kolawole and Anthony McCalla were sentenced to minimum jail terms of between 14 and 17 years each for the attempted murder of a rival gang member and grievous bodily harm in a deadly attack which left a five-year-old girl paralysed from the waist down.
Thusha Kamaleswaran was shot in the chest during the attack while she played in the aisle of her father's shop in Stockwell Road.
Our investigation has discovered that GAS, based in the estates of Angell Town in Brixton, came into existence four years ago. The members were the young members - the so-called "Tinies" - of a dying gang called Organised Crime, or the O.C.
They want on to form GAS which, depending on who you speak to, stands for a number of different things.
The two most repeated are Guns and Shanks (gang jargon for knives) and Grip And Shoot. But then again some would tell you it means Grind And Stack. But there is no definitive answer - this is not an organisation with a headquarters offering explanations.
The gang quickly established itself as a cause of crime and serious violence among young people in the Brixton area. In April, the Kamaleswaran trial heard how GAS could be linked to as many as three quarters of the incidents of serious violence involving young people in the area.
Claire Belgarde is the strategic leader of the Young and Safe programme which works with Lambeth Council to offer support to the 400 young people thought to be involved with gangs in the borough.
"We have a number of gangs and they have their own unique profiles," she said.
"One of the things we do see around GAS is that they have evolved. The young people that would say they are associated with them are living in an area that is multi-generational in terms of these gangs and each generation has a new name for it.
"They are associated with high levels of violence but I would say that is as both victim and perpetrator."
The GAS gang has approximately 50 members who will have varying degrees of association and participation.
The figure most prominently associated with the gang is 19-year-old Agassi Odusina, better known as the rap singer Sneakbo.
But in an exclusive interview with the BBC, he admitted that while police considered him to be the boss of GAS, they were wrong.
"Something happened around my area; someone got killed and I was arrested for it," he said.
"And when I went to jail I'm just thinking 'this is how easy I could lose my freedom and my life' and then the case got dropped and I got out and that's when I started taking music seriously."
Last year, Sneakbo was jailed for breaching the terms of a five year Asbo. He had threatened the lives of a woman and her seven-year-old daughter. In November, Inner London Crown Court suspended his eight-month sentence and released him to pursue his successful music career.
One of his better known raps is "I am a Boss", which helped fuel police suspicions.
Sneakbo strenuously denies allegations that he is or was ever the boss of GAS, adding: "Before I even got nicked for that murder, the police called me the boss of GAS. But I wasn't the boss; I wasn't the boss of anything - it was just the name of the song."
The Metropolitan Police estimates that there are around 250 street gangs in London. In police and council circles, GAS became one of the most notorious.
To a large extent, these gangs replaced the so-called Yardie gangs of violent, predominantly, Jamaican gangsters, who came to London in the 1980s and 1990s to deal in drugs.
GAS is one of the most bellicose gangs in London. It is currently "at war" with three other local gangs: ABM (All Bout Money) in Stockwell; TN1 (Tell No-one) in Tulse Hill; and the Peckham Young Guns across the borough borders into Southwark.
Leading gangs expert Dr John Pitts, the Vauxhall Professor of Social and Legal Studies at the University of Bedfordshire, explained that the GAS gang "very unwisely - got into conflict with a lot of other groups that had fragmented so that there was a point, I gather, where they had a beef - a dispute - with everybody.
"To cut a long story short they bit off more than they could chew. At one point they were riding high and a lot of people were frightened and I think the tide turned when a lot of people worked out that a lot of people were against them."
The Metropolitan Police estimate that gangs could be responsible for one in seven crimes and rapes. More than half of the shootings in the capital are gang-related.
Like many similar gangs, members of GAS are not thought to earn much from their crimes - mainly robbery, petty theft and low-level drug dealing. Detectives at the Trident Gang Command of the Metropolitan Police are most concerned with the gang's trade in death and violence.
Det Ch Supt Stuart Cundy, who heads Trident, told the BBC, "There is no singular gang in terms of why a gang exists or doesn't exist. Some of them are based very much on peer group; some on locality; some on post code. Some are drawn together to further their criminality.
"There is the whole spectrum across London. What we are doing as the Met Police is tackling gang crime in all of its guises.
"Ultimate success for us is stopping the killings... the shooting and stopping the stabbings - stopping primarily young men getting seriously injured right across London."