Detective Senior Sergeant John van den Heuvel, who led the Mei Fan murder inquiry, speaks outside court after the guilty verdict.

Mei Fan was the first of two Wellington women murdered just weeks apart after seeking protection orders against their estranged husbands.

Fan's husband Michael Preston was found guilty on Monday of murdering the Miramar mother of two, and of breaching a protection order against him.

The 60-year-old stood silently as the verdict was read by the jury foreman in the High Court at Wellington.

DAVID WHITE/ FAIRFAX NZ Michael Preston in the High Court at Wellington, where he has been convicted of the murder of his estranged wife, Mei Fan.

The prosecution's case was that Preston was upset about a protection order served on him on November 7, 2013, and killed Fan the next day, stabbing her repeatedly and leaving the knife embedded in her neck.

Two weeks after Fan was killed, another Wellington woman, Sarwan Lata, barricaded herself into her home in the northern suburb of Woodridge to protect herself from her estranged husband, Rajeshwar Singh. He broke in and stabbed her to death.

Lata had a protection order against him, but she did not report many of his breaches of the order.

Preston in China in 2011, believed to have been taken on the set of a television show in which he appeared.

The period immediately after the serving of a protection order was often the most dangerous time for victims of violence, national harm reduction prevention manager Detective Inspector Dave Greig said.

Police had made changes in recent years to the way they dealt with such orders, and a trial was under way in which officers now served them, instead of court staff.

A new recording system made it easier for police to see immediately if a person had a protection order against their name, and victims who had multiple ones.

Another shot of Preston in China, where he met and married Mei Fan. But their relationship was volatile from the start.

Greig said people should not lose confidence in protection orders, which continued to be "valuable". "We encourage reporting, even if it may seem trivial, or at a lower level, or people think police wouldn't want to know about it.

"There is no breach too trivial ... the message to [police] staff is that they must be investigated."

Preston's trial revealed that his descent into obsession and murder began with the breakdown of his marriage to Fan after she joined him in New Zealand in September 2011.

The couple met in her native China in 2003, had two children, and married in 2006.

But there was violence in their relationship. At least twice, Preston was seen to hold a knife on Fan, and once tried to dangle her from a fifth-floor balcony.

With his mother unwell in 2010, Preston wanted to return to New Zealand. By the time he did, bringing the children with him, his mother had died and his father soon followed.

At the same time, Fan met Tani Hoyhtya, a Finn, and the pair had a relationship. However, unable to bear being away from her children, she wanted to follow them to New Zealand.

Preston held off agreeing for some months before supporting her application. She arrived in September 2011 and moved in with him.

But the marriage broke down shortly after, when Fan admitted she had been seeing someone, and Preston kicked her out of the house.

That seemed to start his obsession with getting her deported, and a fear that she would take the children away from him. The obsession became all-consuming, with long-term friends losing patience with him after every conversation became about Fan.

He began a campaign that included writing to members of Parliament, government departments, and police, and telling anyone who would listen about her infidelity and lies, even telling a pastor that she was a helper of Satan because there three sixes in the birth date on her passport.

The protection order was served on November 7, and police believe it was what triggered the murder.

They believe he used rubber dishwashing gloves and carried a witch's hat taken from one of his children's Halloween costumes to hide the knife as he approached Fan on the morning of November 8. He stabbed in the face, neck and arms and left her bleeding uncontrollably on her floor.

Preston has been remanded in custody for sentencing in December.

The couple's two children are now living with a family member, whose identity is suppressed.

The detective in charge of the case welcomed the verdict. "Our thoughts are with the children now who must grow up knowing their father murdered their mother," Detective Senior Sergeant John van den Heuvel said.

"That's going to be difficult for them but they are surrounded by people, like Mei, who love and care for them."

Hoyhtya said on Monday night he felt satisfied by the verdict.

"Justice has been served ... This is a really important step in a very long process."

He planned to travel to Wellington to speak at Preston's sentencing.