A teenage murderer wrote a song about exterminating the weak while he awaited trial.
Theodore Derrick-Hardie, 18, repeatedly stabbed Warren Rosillo in a jealous rage over an ex-girlfriend at a party last year.
Derrick-Hardie spent nearly a year on bail and changed his plea to guilty on the first morning in the High Court at Auckland.
While on electronic bail, he uploaded music to the Soundcloud website under the name "DJ Dark R".
His song included the line: "I exert stress when I export beats that exhilarate the hard and exterminate the weak.
"Execution level next, no way to explain it, I'm XXX bitch, triple x-rated!"
The song, originally recorded by dubstep group Excision, had been remixed and Derrick-Hardie claimed it as his own.
Sensible Sentencing Trust's Garth McVicar said his advocacy group was dealing with increasing numbers of violent criminals glorifying their actions through songs and poems. "There seems to be a recurring and extremely worrying theme. This shows the mentality of the guy - obviously no remorse here - and adds to the aggravating factors the judge must consider."
He called on the judge to sentence Derrick-Hardie to a minimum of 17 years non-parole on September 28.
Rosillo, 18, known to friends as WoF because of his love of cars, was stabbed while trying to break up an argument between Derrick-Hardie and his ex-girlfriend at a party in Pakuranga.
The day after the killing, while Derrick-Hardie was on the run, the girlfriend wrote: "Seeing this was terrifying ... Knowing you were in a relationship with a monster with the guts to murder a innocent younge boy, is undescribable [sic] and eats you alive every second of every minute ... Good luck in prison. Karma will be hell for you. You suffer you selfish jealous lowlife boy."
Rosillo moved to New Zealand with his parents in 2006 from the Philippines.