Prostitute killer Sainey Marong appears to have considered handing himself in to police in the days after he murdered Renee Duckmanton, the Herald can reveal.

The full extent of the Gambian-born butcher's disturbing internet history can now be reported.

Relentless pursuits of Christchurch prostitutes, necrophilia videos, and Google searches on rape and kidnapping feature in data captured by police from Marong's cellphones.

And five days after he dumped Duckmanton's body on May 15, 2016 he started searching for New Zealand Police contact details.


He made multiple searches for "Christchurch central police station contacts [sic] details" and "New Zealand police email contact", while clicking on a police link, "How to report a crime" and stories on other Christchurch prostitute murders, including Mellory Manning's brutal death.

He was arrested on May 26, 2016.

A unanimous jury on Friday took less than an hour to find him guilty after a two-week trial at the High Court in Christchurch.

Sainey Marong was found guilty of murdering Christchurch sex worker Renee Duckmanton. Photo / Supplied
Sainey Marong was found guilty of murdering Christchurch sex worker Renee Duckmanton. Photo / Supplied

The 33-year-old had admitted strangling Duckmanton to death after picking her up from Christchurch's red-light district on or about May 14, 2016 but denied that he meant to kill her, claiming he was insane at the time.

He dumped her body on a country roadside and set her on fire.

Her burning body was spotted in a grass fire on Main Rakaia Rd, just off State Highway One, in the Selwyn area of Canterbury, by passing motorists at around 7.30pm on May 15, 2016.

At 9.08pm, Marong's internet history shows that he Googled, "Selwyn Canterbury" and on the following morning, "Can fire destroy DNA".

That day, as detectives pieced together how the sex worker can came to be brutally slain, Marong read articles online about a body being found at Rakaia.


He also searched, "New Zealand CCTV traffic catching offenders".

CCTV, bank transactions and cellphone records – along with DNA – were central to police building an overwhelming case against Marong.

On May 17, while media reported that police were conducting scene examinations at a Kowhai Terrace property in Christchurch, Marong googled where the street was.

Over the next few days, with police closing in, he researched the Blessie Gotingco rape and murder case, including a Herald article on her killer Tony Robertson's dark past, as well as how a body burns in a fire.

During the trial, Marong gave evidence and admitted that after he had sex with Duckmanton in the back seat of his car after pulling over somewhere in the Templeton area, she then wanted to return to Manchester St.

He said "that voice, that screaming, that yelling was agitating me" and the dispute "triggered something very serious".

"The only method I could use to stop it was to compress her neck," he said.

Marong's internet history, released by the court this week, shows that as far back as February 2016, he was obsessed by Christchurch prostitutes.

Sainey Marong, found guilty of murdering Christchurch sex worker Renee Duckmanton. Photo / Supplied
Sainey Marong, found guilty of murdering Christchurch sex worker Renee Duckmanton. Photo / Supplied

He spent hours searching for "Christchurch cheap escorts" and checking out girls from escort agencies.

Giving evidence, he admitted hiring prostitutes several times a week and cruising the red light district as often as 10 times a day.

But by March, the searches started taking a sinister turn, with Marong looking up chloroform and its New Zealand suppliers.

Kidnapping and necrophilia were soon featuring heavily, including an article entitled, "How to kidnap a girl: an informative guide", and searches for, "Kinapped [sic] and raped", "Man having sex with dead body", "Having sex with the dead", and "Preserving dead body in freezer then sex porn".

Marong denied that he had sex with Duckmanton's dead body, despite the Crown putting it to him that it was a fulfilment of a twisted sexual fantasy.

The jury dismissed Marong's claims that he had been "disconnected from reality" at the time he killed Duckmanton, and that from May 6-17, 2016, he was poisoned by kidney failure that resulted in urine "travelling in my brain".

A psychiatrist and a psychologist, who both assessed Marong before he stood trial, concluded that he did not meet the criteria for a defence of insanity.