The mother of three-year-old Moko Rangitoheriri, who was tortured and abused to death, lashed out at his killers and the legal system at Rotorua's High Court on Monday.
Tania Shailer and her partner David William Haerewa were sentenced to 17 years in prison for the boy's manslaughter in August last year.
In an emotional victim impact statement to the court, Moko's mother Nicola Dally-Paki said, "When I think of them, I think of them as evil."
"Because of Tania and David's actions, I had to bury my son."
She asked Justice Sarah Katz to impose the maximum sentence on the pair, saying "I don't believe you are truly sorry," and criticised the charges being reduced from murder to manslaughter -- which she believed was to save the Crown money.
The downgrade shocked the nation, and prompted national rallies across New Zealand.
The couple will serve at least nine years behind bars before being considered for parole.
Watch the video for Nicola Dally-Paki's full statement.