A New Zealander has been sentenced to at least 30 years in jail in Australia for the "chilling" murder of Sydney man Morgan Huxley in September 2013.

Dressed in a grey suit, the 22-year-old Daniel Jack Kelsall stared straight ahead and made no expression as Justice Robert Allan Hulme sentenced him to a maximum term of 40 years, saying it was a chilling case of murder.

Justice Hulme said during sentencing he was unable to say if Kelsall killed for the thrill of it or if it was as a result of fantasy or obsession.

But he said it was entirely senseless and needless and must have been the doing of a very disturbed mind.

Huxley's family say they are haunted by how their loved one spent his last moments and are plagued by the question, "Why?".

Kelsall, who is adopted, remained behind in Wellington when his parents moved to Australia in 2010, and moved to Sydney in 2012.

He will be eligible for parole in January 2044.