The last messages sent from a backpacker who died told a friend a date with a man accused of her murder was going "really good".

Grace Millane from Wickford was messaging a female friend from university during her date, the court heard.

A letter by her friend, Ameena Ashcroft, was read to the jury and said Ms Millane referred to "getting smashed" on the date and said the encounter was going "really good".

"'Mate, he lives in a hotel'," Ms Millane messaged Ms Ashcroft.

"'You have to go to his apartment in the hotel, bet it's like the top floor'," Ms Ashcroft replied.

"'He is coming to London next year'," Ms Millane wrote. She then sent what would be her final message: "'I click with him so well.'"

Detective Samuel Luker conducted the examination of the defendant's apartment in the hotel at 9.55pm on December 6.

He told the court: "I was looking for Miss Millane, but the room was empty."

He did find an empty suitcase and two mobile phones - including one belonging to the defendant - and returned to the scene the following morning to continue his investigation.

Gillian Millane, the mother of the deceased woman, left the court in tears as Mr Luker described a series of photographs found on the defendant's phone.

Those photographs showed intimate parts of a woman's body, the detective said, which the Crown has alleged are of Ms Millane.

He added that the phone's records also showed pornographic websites were accessed around the same time.

The defendant did not react as Gillian Millane walked out of the courtroom.

Mr Millane looked directly at the defendant as the detective confirmed pornography was looked at on the defendant's phone.

But he cast his eyes down when he heard the defendant had searched online for "rigor mortis".

The data showed the man had used Google to browse websites for large duffel bags, suitcases and car hire.

The defendant's phone also searched for "flesh-eating birds" and "are there vultures in New Zealand?" days later on December 5, 2018.

The expert who led the scientific investigation of the apartment where young English woman Grace Millane was allegedly murdered has begun testifying in Auckland High Court.

Scientist Dianne Crenfeldt, from the Institute of Environmental Science and Research (ESR), told the jury she had located two approximately circular probable blood stains between the accused's bed and a wardrobe.

The smaller of the stains was more circular and "could have come from a bucket", Ms Crenfeldt said.

She added: "The shape of the probable blood staining and the presence of blood on the floor provided strong support that clean up of blood had occurred in this area."

Ms Crenfeldt told defence barrister Ian Brookie under cross examination that luminol testing showed that someone with blood on their feet had walked around the apartment, she said.

She was also asked how accurate the chemical was in testing for the presence of blood.

Mr Brookie said: "If someone has mixed blood with a cleaning product and moved it around, this could distort the original blood stain, correct?"

Luminol was highly sensitive and indicated the presence of blood and could also show evidence of a clean-up, Ms Crenfeldt said.