Abraham Badru’s mother believes he was murdered as revenge for testifying against a gang of boys who raped a girl on the Frampton Park Estate in 2007.

And the Gazette can reveal one of the boys he helped convict was also killed in December. Alexander Vanderpuye, 24, was stabbed off Cassland Road at 4.45pm on December 7.

Aged 15, Alexander had been jailed for six years for his part in the horrific attack on the 14-year-old girl.

Abraham, who had stepped in to save the victim, had given evidence during the trial that saw nine members of the Kingzhold Boys gang jailed for a combined 54 years. He did so despite receiving threats and having his home pelted with eggs.

Three men who were arrested over Alexander’s death have been released under investigation. Scotland Yard told the Gazette detectives were “keeping an open mind about the motive for his murder” and there were various lines of enquiry.

Abraham, 26, was shot yards from his mother’s house in Ferncliff Road, Dalston, on March 25. He was on the phone to a friend when he was killed.

The Liverpool fan, who was hoping to start a PhD, had been given a police bravery award in 2009 for his actions. Police have stressed revenge is just one line of inquiry, and that the shooting may have been mistaken identity.

But his mother Ronke said yesterday she believed it was the reason he was gunned down.

She said the intimidation he received had left him “scared for his life” so he moved to Bristol aged 16 to do his A-levels and stayed there until completing his Master’s degree.

He returned to London two years ago to look for work and had to run away after bumping into one of the attackers in a nightclub. He had his car mirrors and windscreen smashed and the tyres were stolen.

Abraham had asked to be moved out of Hackney but feared his application would be rejected and began saving for his own home. He was hoping to leave this year.

Recalling the moment she was told her son had died, 50-year-old mental health worker Ronke said: “I started shouting: ‘My only child, my life is empty’. I started rolling on the floor.

“I was like: ‘Who would choose to do this to Abraham? Who has he offended to that extent to take his life away?

“He was a very peaceful man, he wasn’t violent at all. A very respectful boy and a loving child. He loved everybody and was always at peace with everyone.”

Police say his killer, who may have been lying in wait, was riding a white bike. He is believed to have emerged from an alleyway, shot Abraham twice and then escaped via another alleyway.

Det Ch Insp Noel McHugh said: “We are now a month on and every day his family have to live knowing the person who did this is still out there.

“Someone knows who killed Abraham; I have said the answer lies in the community and I still believe that.

“If you are reading this and you want to contact us but are concerned about your safety, I can assure you your information would be treated in the strictest of confidence and sensitivity.

“Help us do the right thing and bring justice to Abraham’s grieving family.”

Officers want to trace four people who were near the scene but have not yet come forward.

They want to speak to:

– A person who walked along Langford Close and then turned into Ferncliff Road just before the murder

– A person in a three-quarter length puffa jacket opposite the day centre in Ferncliff Road at the same time

– A man in dark clothing with a good up and light trainers who was speaking on a phone in Ferncliff Road seconds after the shooting, as Abraham lay on the ground

– A black man, about 5ft 8in with a bushy Afro who was wearing a long-sleeved grey top and ran into Foxley Close from Ferncliff Road just after the shooting

A map outlining the scene can be found here.

Mr McHugh added: “We are particularly keen to hear from anyone who saw a male cycling in the area around the time of the murder on a white bicycle - this could be the killer.”

Police returned to the scene of the murder yesterday, a month since the killing. A £20,000 reward is on offer for information leading to the arrest and prosecution of the murderer.

Anyone with information can contact police on 020 8785 8099, via 101 or @MetCC. Or to remain anonymous call Crimestoppers on 0800 555 111.

Additional reporting by Press Association.