A teacher told Mei Fan's son to say goodbye to his mother properly, not realising it would be the last time he'd see her alive.

Ms Fan, 37, was killed in her Miramar home later that day in November 2013, and her body was found two days later.

Her estranged husband Michael Preston, 60, is accused of her murder and is on trial in the High Court at Wellington.

Giving evidence before a jury today, the teacher - who cannot be named - said Ms Fan's son was annoyed his mum told the teacher he hadn't done his homework.

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"I could sense that friction and I couldn't let her just go away under those circumstances. So that's why I called him over and told him he needed to say goodbye."

Michael Preston is accused of the murder of Mei Fan. Photo / Supplied
Michael Preston is accused of the murder of Mei Fan. Photo / Supplied

Footage from the crime scene in Brussels St, Miramar, showed the inside of a home largely undisturbed after Ms Fan was killed.

Jurors saw footage of Ms Fan lying in the laundry floor, blood surrounding her, and a knife still in her neck.

Preston watched the video from the dock, taking notes at times.

A statement from Constable Rory Spray was read to the court, mentioning a previous visit to the Brussels St house.

"I told Sergeant Hughes that I had been to the address previously in relation to a family violence incident a couple of months earlier and had spoken with a Chinese lady and her children who lived there."

Jurors also heard details of a protection order for Ms Fan issued on November 7, the day before she was murdered.

Detective Nicole Bourke, who obtained and analysed Ms Fan's phone data and internet usage for the three months up to the day she was found dead, will give evidence this afternoon.

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The last message Ms Fan sent was to her partner Tani Hoyhtya the night before she was murdered.

Ms Fan's internet usage plunged on November 8, Ms Bourke told the court this afternoon.

An analysis of data usage suggested to her that Ms Fan last used the internet between around 6.42am and 7.42am that day, she said.

Preston, who has a back condition, asked Justice Joe Williams if he could stand during the afternoon session. The Judge allowed him to do so.

Ms Bourke told the court there were 12 missed calls to Ms Fan's landline and cellphone on November 8.

Detective Jana Peterson, who analysed Ms Fan's Toshiba laptop computer usage, said he refined a spreadsheet received from the electronic crime lab.

An analysis showed numerous "log-ons" and "log-offs" on November 6, and the computer's last log-off was last used at 6.31pm the night before Ms Fan was killed.

On November 8, there were no log-on or log-off events. There was also no activity the following day.

Mei Fan 'was scared of Michael'

Cindy Dalziel, a friend of Ms Fan, was called to give evidence this afternoon.

On Guy Fawkes, 2013, Ms Fan sounded "very upset and stressed out", Ms Dalziel said.

"She said that Michael been around, I don't recall why, but it was a big argument apparently."

Ms Fan told her friend Preston had arrived at the Brussells St house on a pushbike.

Both women visited a lawyer to make sworn affidavits and Ms Fan soon after received a protection order.

Ms Dalziel told the court that Preston once told her: "You're not going to be friends with Mei for much longer as she was being deported to China."

Justice Williams said Ms Dalziel had a support person with her to help reduce the stressful impact of giving evidence.

Ms Dalziel lived in Miramar at the time of Ms Fan's death.

She met Ms Fan at a children's hockey game. She said Ms Fan moved into the Brussells St house in April 2013.

"We became very close," Ms Dalziel said.

The two women had children of a similar age and spent a lot of time together, sometimes during 'play dates' the youngsters had.

Ms Dalziel said Ms Fan told her about how she and Preston met in China a decade earlier, and moved in together.

"She was looking for a teacher because she ran a school...she said that's how she found [Preston], on the internet.

"She put up quite a bit of money and Mr Preston didn't have as much."

Ms Dalziel understood the couple separated in 2011. Preston came to New Zealand for his mother's funeral but didn't go back to China, Ms Dalziel said.

Ms Fan came to New Zealand to make "a go" of reuniting with her children, she said.

"Eventually she just couldn't live without her children anymore..."

But Ms Dalziel said Ms Fan was soon kicked out of Preston's house, and went to stay in a Women's Refuge.

"She did mention that she wanted to sell the apartments in China...Mr Preston wanted her to go over and sell the apartments so that he could have the money because it was his."

Ms Dalziel also relayed an encounter with Preston, in which she claimed Preston told her: "People are trying to kill Mei.

Ms Dalziel said her friend was usually sad on Fridays, because Preston would take custody of the children then.

"She was scared of Michael," Ms Dalziel added.

Court has adjourned for the day and Ms Dalziel will continue giving evidence tomorrow morning.

- Additional reporting: John Weekes of NZME News Service