Bruce Emery, 52, will be released from jail next month after the Parole Board decided he was at low risk of reoffending.
Emery had been jailed in February last year for four years and three months after stabbing to death teenager Pihema Cameron, whom he caught spraying graffiti on his south Auckland property.
Pihema Cameron's mother Leanne Cameron said the Parole Board had not contacted her or her family to let them know Emery would be released, The Herald on Sunday reported.
Now living in Australia, she said she found it "disgusting" that he would soon be free, having served less than half his sentence, and it seemed like he was getting away with killing her son.
A Parole Board spokesperson said the family was not contacted because they did not register as victims, which would enable them to be a part of the parole process, the paper reported.
Parole was rejected when Emery first became eligible in April 2010 as there were concerns about his proposed release address and the board was not satisfied he did not pose an undue risk to the community.
When he reappeared in July the board had concern "over the management of his mood" and called for a psychologist's report.
That report, dated last month, said Emery, a first offender, "presents at a low risk of violent recidivism and low risk of general offending".
It said he would receive treatment recommended by the psychologist, and that Emery "is also clearly aware of the difficulties his mood may present and intends to seek appropriate help".
Emery told the board he had no intention of returning to his previous address, and planned to move away from that area to another part of the country in the near future.
