A Wellington man who shook his five-month old stepson to death last year will spend at least 14 years in jail.
William Wakefield, 32, was found guilty of murder last month, and sentenced in the Wellington High Court on Friday.
Wakefield sat in the dock, as Justice Robert Dobson described what he called a "ghastly form of murder".
"This involved the worst breach of trust, and how completely vulnerable Lincoln was - he was utterly defenceless, completely dependent on your basic humanity to treat him kindly and carefully," Justice Dobson said.
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Wakefield initially denied hurting five-month-old Lincoln, but prior to his trial he pleaded guilty to manslaughter.
He says he intended to hurt, not kill, because he was "gutted" the boy wasn't his son.
But despite his remorse, he was last month found guilty of murder.
"Baby killings by men who are not the biological father of their partners children happen far too often in New Zealand," Justice Dobson said. "It is [a] real blight on the way we live, and it should not happen in a caring society."
Lincoln's mother has name suppression, but in a victim impact statement, said she hopes Wakefield is haunted by the day he picked Lincoln up and looked into his big blue eyes, before brutally shaking his little body in his big hands.
Wakefield won't be eligible for parole until he is at least 46 years old.