A New Zealander accused of a prison murder in the United States faces another trial after a San Diego jury couldn't decide what he was guilty of.

Aucklander Clinton Thinn, the step-brother of National MP Nikki Kaye, has been on trial for the alleged strangling of his cellmate Lyle Woodward at a jail in San Diego in December 2016. He was behind bars for an earlier botched bank robbery.

The prosecutor was asking for a first-degree murder conviction but the jury was split three different ways, Star News reporter Neal Putnam, told RNZ on Monday.

"They all thought he was guilty but they couldn't agree on what the crime was, whether it was first-degree, second-degree or voluntary manslaughter."

"The jury was a little frustrated, they said they tried but just couldn't do it," he said.

Putnam said that the prosecutor announced straight away she was going to retry Thinn for first-degree murder, with a trial date to be set on February 28.

Thinn's lawyer argues the 29-year-old was targeted for his accent and had no choice but defend himself after Woodward attacked him prior to the incident.

If convicted of first-degree murder, Thinn could face up to 25 years in jail.

- NZ Newswire