Accused killer Michael Preston knew details about the brutal stabbing of his estranged wife Mei Fan that only police and the murderer would know, the Crown has told a jury at his trial.
In a conversation with a journalist, Preston told him that Ms Fan was found with a knife in her neck but police had not released that information to the public.
Preston, 60, is accused of murdering his wife in November 2013 in her Miramar home after their relationship fell apart.
Detective Senior Sergeant John van den Heuvel told the trial at the High Court at Wellington that the evidence from their investigation was stored on secure servers and in a locked room at Wellington's central police station.
"Everything uncovered was kept strictly confidential," he said.
"I am not aware of any breaches of the security by anyone throughout the Operation Brussels."
But the defence countered that if there was a breach, he may not have been aware.
"I would find it unlikely," Det Snr Sgt van den Heuvel said.
"I am not aware of any breaches and I expect to know if there was."
Another witness, Housing NZ tenancy manager Christine Hannah denied an earlier claim that she and Preston had a close relationship, saying she only spoke to him on five occasions.
They had spoken about Ms Fan's murder when Preston applied to move properties so he and their children could have a fresh start.
The particulars of their conversation included talk about a broken ranchslider, and a black plastic tarpaulin between the laundry and the lounge room she had seen during an inspection of Fan's property with police.
But when asked whether she told Preston that Ms Fan was found with a knife in her neck, she replied: "No".
"I don't have any knowledge of what happened to Mei," Ms Hannah said.
The court also heard Preston sent to Ms Fan's boyfriend Tani Hoyhtya an email in March 2014 accusing the Finnish national of organising an Asian or New Zealand hitman to murder her and he should turn himself into police.
"How sweet, how naive, how pathetic," Preston goaded Mr Hoyhtya about wearing the ring he wanted to propose to Ms Fan with as an earring.
"You're such a clever, cunning hunter aren't you?
"Do the right thing Tani."
The trial continues.