A 17-year-old was convicted of murdering a former friend he knifed 12 times in the back in Scarborough.
Macauly Jenkinson was only 16 when he launched a ferocious attack on Michael "Angel" Graham, 19, on the Scarborough seafront in April.
He was convicted by a majority of 11-1 of murder, and wounding with intent on another teenager, who cannot be named.
Judge Simon Bourne-Arton, the Recorder of Middlesbrough sitting at Teesside Crown Court, lifted reporting restrictions on the media identifying the defendant because of the public interest in the case.
The jury was told Mr Graham and his attacker had been friends but fell out when Mr Graham taunted Jenkinson over his relationship with a girl which started when he was 15 and she was 14.
After the guilty verdicts, Tom Roberts QC, prosecuting, said the offences were aggravated by the ferocity of the attack, from behind on the defenceless victim.
Jenkinson had assembled a group of youngsters and had encouraged them to arm themselves and support him, the barrister said.
It happened in front of a group of youths, some as young as 14. The seriousness of the case was also aggravated by it taking place in public, on the seafront, he said.