The authors of a “misguided” and “sick” campaign encouraging witnesses not to come forward in shooting cases are former police informants desperate to use their experiences to force reform of witness protection (WP).

The Stopsnitching (SS) campaign, which began when it leafleted the area where Streatham teenager Sylvester Akapalara was killed, caused further outrage when it dropped leaflets warning witnesses to the shooting of five-year-old Thusha Kamaleswaran in Stockwell not to give information to police.

It was widely reported to be the work of gangsters but, speaking on condition of anonymity, the group said the campaign was created as a subversive reaction to the group’s perceived “abandonment and isolation”.

They said they understood why SS was branded sick by some media and irresponsible by police – Thusha, who was blasted in the chest in a shop in Stockwell, was put in an induced coma and may never walk again after her spine was shattered. But, they said, their motivation was to expose failings with WP - which was like being in “a mini Guantanamo” - and argued only a shock campaign would lead to exposure and reform.

One man who came forward to a murder claims he was denied witness protection because of his nationality – a claim the police force involved strongly denies.

The man (we will call John) said: “I can see people see it is sick and agree [victims’] families will be aggrieved by it, but revenge isn’t the motivation. “If the conviction rate starts coming down and police and politicians are suffering for it and people start asking questions then maybe eventually it will turn around.

“It’s horrific and sad people lose their children, but I came forward to do the honourable thing.... [We want to] help people who are prepared to give up their liberty for justice. Our motivation is not to let murderers get away.” But Claudia Webbe, chairwoman of the independent advisory group for the Metropolitan Police’s Operation Trident, which deals with gun crime in London’s black community, said the campaign was “misguided and wrong”. She said: “I can’t condone or support [the campaign] because it hurts vulnerable communities who are most at risk from violence and already live with the cloud of intimidation and fear [hanging over them].”

A spokesman for the Metropolitan Police said WP was “absolutely vital in helping make a stand against criminals” and “had a successful record that has resulted in many witnesses agreeing to give evidence.”

The group said their collective experiences – which cover four police forces across England over several years – proved the system was failing to protect victims, witnesses and the public or help police obtain convictions There are about 1,000 people in the UK in WP but each police force has a separate budget.

A review of WP, conducted by the Ministry of Justice and the Association of Chief Police officers has been under way since May last year, but has no date for completion.

John said the group decided to create a “gangster” campaign as leaflets with details of their personal stories would have been dismissed as people “pissed off with the police and preying on the misery of others”. He said a subversive campaign was the only way to get their voices heard. The group claim to have had three-and-a-half hits on the Stopsnithcing.info.

The group has suggested a number of changes, chiefly the creation of a national WP programme - monitored by an independent body that could review complaints.

They said a booklet setting out minimum police obligations and witness’ rights should be handed out at the initial police interview – with an independent liaison officer present.

John’s lawyer, present when he gave his police statement, described his client’s evidence as “very strong”.

He said: “Somebody independent has to be there [at the interview]. I don’t want to criticise the police because they have a tough job but . . . if there was more guidance maybe more people would come forward.”

Iffat Rizvi started charity STARR – which deals with the families of victims of gun crime - after her daughter Sabina, aged 20, was shot dead in 2003, and has sympathy with the group.

“Witnesses shouldn’t be treated like criminals” she said. “I can understand [the campaign]. “Police have to do more to protect witnesses, in the courts and after. There are many groups that can provide support, but we have to give witnesses those connections.”

“Witnesses are hidden from society, they live in fear,” John said, “It is like being in a mini Guantanamo Bay.”

“No one wants to hear our story, Gavin added, “after all who cares about snitch's. After all we are scum for coming forward.”

In John’s case he lost his family and identity, the family victim of the dead man did not see justice and police did not secure a murder conviction – potentially leaving killers still walking the street.

Three men, including Anthony McCalla, 19, of Oakdale Road, Streatham, have been charged with the attempted murder of Thusha Kamaleswaran and 35-year-old Roshan Selvakumar – who was also shot in the incident in March. Five men have been charged with the murder of Sylvester Akapalara, who was shot and killed in Peckham on December 29 last year. For much more on this, visit streathamguardian.co.uk.