A man in a frenzied state of rage and jealousy bombarded his ex-girlfriend with hundreds of menacing text messages before he murdered a stranger in her Melbourne driveway.
Nathan George West, 21, plunged a knife into the back of Dale Cheney as the 17-year-old left the home of West's former partner Melanie Johns.
Victorian Supreme Court Justice Elizabeth Curtain jailed West for 20 years on Friday, saying his crime was motivated by misplaced jealousy.
"This was as pointless and senseless a death as one could imagine," Justice Curtain said.
"You were driven by an uncontrollable rage and jealousy.
"A young life was so cruelly ended in such a senseless and self-indulgent act."
West did not know Mr Cheney but was furious he and another man, Corey Semmens, had been staying at Ms Johns' Sunbury home.
In the lead-up to the murder Mr Semmens had taunted West, sending him messages that said he had been sleeping with Ms Johns.
West in turn sent 434 text messages to Ms Johns, who replied to some, by the morning of the murder on September 30, 2012.
But Justice Curtain noted there had been no communication between West and his victim.
"You did not know him, you had never met him and had nothing to do with him," she said.
West selected the largest knife from a friend's kitchen, and told her "he's there, I'm going to ..... stab him" before driving to Ms Johns' home.
Once there he sent 20 text messages and tried to call her six times.
He left when Ms Johns and Mr Cheney came outside to speak to him, but returned minutes later and attacked Mr Cheney as he stood alone in the driveway.
Justice Curtain said Mr Cheney was a popular young man who was adored by a family left stunned and appalled by his murder.
"In Mrs Cheney's words, Dale 'was murdered for no reason by a stranger. It is unbelievable'," she said, quoting from the victim statement of Mr Cheney's mother.
Justice Curtain noted West's guilty plea and that he had suffered mental health issues which were exacerbated by his use of illicit drugs.
West's mother collapsed in tears as Justice Curtain read out the 20-year sentence.
West, of Sunbury, must serve a minimum of 16 years.
