The sister of Highbury bus stabbing victim Derek Boateng has called for justice after branding her brother’s knife-wielding killer “pure evil”.

Gifty Boateng, speaking from the family home in Hackney, also paid tribute to “a lovely brother” who was “friendly with everyone” on behalf of his family who she said are distraught.

Police today confirmed one line of inquiry is that the 15-year-old being held on suspicion of attempted murder came from an east London gang, which we have chosen not to name, nearby to the victim’s home.

It is understood Derek was friends with members of the rival London Fields gang but was never a member.

The life of the tragic 16-year-old was cut brutally short on his birthday just hours before he was due to celebrate it with friends and family on Tuesday who paid tribute to a boy who “would never harm anyone”.

He had been travelling home on the 393 bus from college, according to friends, despite normally catching the train home.

Ms Boateng, 29, revealed how family and friends gathered round Derek’s death bed for more than 24 hours “praying for a miracle” while he was wired up to a life support machine.

She said: “We were all praying and we were hoping for a miracle.

“He was only breathing because of the life-support. Everything in him was damaged. I have never seen anything like that.

“I mean whoever has done it, I don’t know whether they have the person, but whoever has done it, they need to be punished.

“The person is pure evil and I just don’t know why they would do it, especially on that day, his birthday.

“We can’t believe what is happening, everyone is in shock. We are expecting him to walk back through that door.

“He was just a child and so quiet. He was just a normal 16-year-old.

“The last time we’d talked to him, he was saying that he was going to go out with his friends and was just excited about his birthday.

“He was a lovely brother and very friendly with everyone.”

She paid tribute to his resolve to become an engineer when he grew up and his talent for drumming and playing football.

Lois Tape, 16, a long-term friend, said: “He wasn’t a bad guy at all. He would never harm anyone else.

“He was the kind of guy that if his parents called him to go home he would listen. He was a good son. It’s just a massive shock.

“He was just going home from college. He usually would take the train. I don’t understand why he took the bus this time.

“I saw him Monday. I just can’t believe it. We were just catching up and next thing I know he’s been stabbed and now he’s gone.

“He was such a popular guy. His charisma made him popular. He had a good sense of humour.”

Detectives today launched a murder investigation after the teenager was stabbed on the bus in Highbury New Park at the junction with Holmcote Gardens near to Highbury Grove School.

He was airlifted to hospital on Tuesday when he turned 16 but died last night after losing his battle with the inflicted wounds.

A 15-year-old continues to be held on suspicion of attempted murder at a north London police station after officers obtained a further 24-hour detention warrant from the courts. A post-mortem is being scheduled.

Derek attended Regent’s Vocational College, Hackney, but was a former pupil at Highbury Grove. Police are appealing for witnesses of the attack shortly after 3pm on Tuesday.

Onlookers spoke of their horror as they watched paramedics attempt to give the teenager life-saving treatment for several minutes on the single deck bus, which performed an emergency stop near the school where the air ambulance landed.

Witnesses can call police on 020 8345 3734 or Crimestoppers anonymously on 0800 555111.