Mark Parrish, 37, plunged a knife eight times into Christopher Taylor after seeing the 25-year-old row with his girlfriend in the street.
Parrish just happened to passing as Mr Taylor as he argued with partner Jamie Girvan outside a New Year's Eve party in Harold Hill, Essex.
The court heard Parrish had become engaged to his own girlfriend earlier the same night but lost his temper when the night 'turned sour'.
When he saw the other couple arguing, he shouted: 'Get your hands off her' before stabbing Mr Taylor in the chest, back and side in the early hours of January 1, 2004.
Barry Edwards, Mr Taylor's uncle, was also stabbed three times as he tried to fight Parrish off with a beer bottle.
Despite the attack happening more than seven years ago, Parrish was not caught because there was no scientific evidence at the scene linking him to the crime.
He was only charged last year after four former girlfriends told police he had confessed to the crime.
Parrish, who has since married and had two children, was convicted of murder and attempted murder by a jury after a two-week trial. Read More