The Google history of a butcher accused of murdering Christchurch sex worker Renee Duckmanton "deeply implicates" him, the Crown says; it includes alleged searches for kidnapping and necrophilia, and an article entitled, 'How to kidnap a girl: an informative guide'.

Sainey Marong, a 33-year-old originally from Gambia, picked up Duckmanton from Christchurch red light district, before strangling her to death, dumping her body on the side of a country road, and setting her on fire, the High Court in Christchurch heard today.

Marong denies murdering Duckmanton on or about May 14, 2016.

The Crown outlined its "overwhelming" evidence in an opening address to a jury of nine women and three men this afternoon.

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The court heard that while her client, who the Crown alleges was Marong, was at a cash machine, she spoke to her boyfriend Samuel Doak.

She allegedly told Doak that she was with the same client who had locked the car doors on her about three weeks earlier, and she had to walk home from a job.

Giving evidence today, Doak said he asked her if she was sure she felt safe.

Security camera footage of Renee Duckmanton walking on Peterborough St in Christchurch. Image / Police
Security camera footage of Renee Duckmanton walking on Peterborough St in Christchurch. Image / Police

"'Yeah yeah, I'm fine. Stop ringing because he's getting annoyed'," she allegedly told Doak. They told each other they loved each other and hung up.

It was the last time they spoke, the court heard.

Doak then text his girlfriend asking for the street name and number of the house she was going to.She text back to say they had "parked up", been paid, and that Doak should ring her at 10.30pm.

Doak says that struck him as being "odd" and when he tried ringing her, he got a text back saying, 'I'm coming babe', which also struck him as "an odd thing" for her to say.

The next time he phoned, it went to voicemail.

"I tried calling heaps of times. I couldn't get hold of her," he said.

"I was really worried after she wasn't answering her phone. It was really unusual. "Nothing was making sense ... Something just didn't feel right."

Doak earlier said that they were both using drugs at the time - methamphetamines, synthetics and cannabis – paid for by her street earnings, along with food, rent and smokes.

She always used condoms with customers, he said, and she worked under the aliases of either Alena or Alana. She had just dyed her hair red.

Doak said they had "sort of always agreed" that she wouldn't go to client's homes, but that fateful night, "we didn't follow that".

Crown prosecutor Sean Mallett earlier said Duckmanton left her Cashmere home for work at 8.09pm on May 14, 2016.

She was picked up by her minder and went to her usual corner at the intersection of Manchester and Peterborough streets.

Duckmanton, the court heard, texted her boyfriend at 9.05pm to say she had a job paying $100.

The Crown alleges the client was Marong.

CCTV will show, Mallett said, a silver Audi belonging to Marong driving past her corner several times before eventually picking her up.

Eight minutes later, Duckmanton phoned her boyfriend again to say the client wanted to go back to his house, and that job was now worth $300. She also texted her minder.

The Crown alleges it has CCTV footage and evidence of Marong getting $300 out of a cash machine.

A final text to her boyfriend was sent at 10.23pm. It then went to voicemail after that and her phone has never been recovered.

The following day, at around 7.30pm, members of the public noticed a fire on the grass verge at Main Rakaia Rd, near State Highway 1.

They stopped and made the grisly discovery of Duckmanton's half-naked and burning body.

During the police scene examination of Operation Lightning, they found a lighter, beanie, and "bizarrely", Mallett said, a sheep's tongue. They are all allegedly linked to Marong.

A halal butcher will give evidence that on the day of the murder, Marong had a sheep slaughtered, and will allege that he removed the animal's tongue with knives he had bought with him.

Testing shows the tongue found where Duckmanton's body was found is from the same sheep slaughtered that day.

DNA samples taken from Duckmanton belongs to Marong, the Crown alleges.

However, Mallett said while it suggests sexual intercourse took place, it can't be determined whether it happened before or after her death.

Duckmanton's hair was also allegedly found in Marong's car, the court heard, and in his vacuum cleaner.

The Crown alleged that the day after her body was found, he bought cleaning products and rubbish bags.

Police examinations of Marong's mobile phone, the Crown alleges, "deeply implicates" him in the murder.

Weeks before the alleged murder, the Crown says Marong searched for what kidnappers use to make people unconscious, chloroform, and is claimed to have clicked on an article entitled, 'How to kidnap a girl: an informative guide'.

There were also multiple searches about necrophilia, including a "man having sex with dead body".

Marong was arrested on May 26, 2016.

When interviewed, he exercised his right to silence to most questions except at one stage when he said he had been "mentally and physically unwell", the Crown alleges.

While awaiting trial in custody, Marong is alleged to have told a Corrections officer, "If I was in my own country, I would be taken outside and killed for what I did".

He also allegedly told a prison guard when asked why he did it, that it was "like hunting in the wild", and that it was "brutal what I did to her. She didn't deserve it".

Marong is represented by defence counsel Jonathan Krebs.

In a short opening address, Krebs encouraged the jury to keep an open mind.

What they will hear during the trial may best be understood and rationalised through "a lens of mental imbalance", the lawyer said.

The High Court trial is the first to be held at Christchurch's new courthouse, part of the $300 million justice and emergency services precinct.

Justice Cameron Mander earlier instructed jurors to set aside any feeling of prejudice or sympathy and to remain entirely objective.

The trial is expected to hear from more than 80 witnesses and is set down for three weeks.