The court battle over a gold medal stag with a mighty set of antlers has been declared a mistrial after the defence claimed they had been surprised by the prosecution’s argument.

Three men are accused of poaching a stag off the game reserve Mountain Hunters NZ, which is owned by Adrian and Brent Moody.

The judge alone trial of Anthony James Fraser, his brother Travis Fraser and friend Shayne Parry – who deny the charge of theft of an animal worth over $1000 – started in Masterton District Court on Monday.

Two minutes before the trial started, the defence produced a photo which seemed to show two of the men with the dead stag on the property of Bluemaris, where they had been given permission by the owner, Mike Taylor, to hunt.

Originally, the prosecution was going to argue that the deer’s head was passed over the fence.

After the late introduction of the photo, the prosecution – led by Sergeant Jason May – had to forward the idea the head might have been detached but repositioned in front of the slain beast for the photo, or that the intact carcass could have gone under the fence that separates the two properties.

Expert witness Neil Mercer was to be called to comment on instances when he had moved the body of a stag under a fence.

But lawyer Kevin Smith, representing Parry, said the defence had been hindered by the failure to disclose, as that was not in the evidence brief.

“The prosecution has had since April 2016 to get its case together,” he said.

Mr Smith sought a mistrial because it was “unfair and in breach of the rules”.

“The obligations of the prosecution are quite clear under the rules.”

Travis Fraser’s defence lawyer Fionnuala Kelly said she too rejected new material being entered by a witness at the last moment.

“It does have a very negative effect,” she said.

“It seems the prosecution is shifting its case as we go.”

Sergeant May said it had happened because the defence had introduced the photo at 9.58am on day one, when the trial was due to start at 10am.

In light of that, the case theory had changed.

It was impossible for him to provide the expert response any quicker, he said.

“It’s specifically about whether the animal would go under the fence.

“Mr Mercer would give you that he has done this many times himself.”

Mr Smith said that type of evidence was so “precise” that the defence should have been able to have the time to provide experts who could rebut it.

Judge Barbara Morris said the defence could “keep their powder utterly dry” and use surprise tactics if they wished.

“If the prosecution wants to challenge the ambit” the only way to “ensure fairness” was to start the trial again.

After an adjournment, Sergeant May decided the trial needed to be restarted.