Renee Duckmanton's murderer arrived in New Zealand on a fake passport and was about to be deported, it can now be revealed.

Suppression orders on details of how Sainey Marong arrived in New Zealand have now been lifted.

Marong, a 33-year-old butcher originally from The Gambia, was found guilty of murdering Christchurch sex worker Renee Duckmanton by a unanimous jury after a two-week trial at the High Court in Christchurch last month.

He had admitted strangling her to death after picking her up from Christchurch's red light district in May 2016 but denied that he meant to kill her, claiming he was insane at the time.

Now it can be revealed that Marong arrived at Auckland Airport on a flight from Melbourne via Hong Kong on a fake passport on January 10, 2014.

He destroyed the passport at the airport, the court heard.

While Marong had been living and working in New Zealand legally for a period, he was in the country illegally at the time he committed the murder.

Marong was born and raised in Gambia's capital city of Benjul as a member of the Mandinka tribe.

After secondary school, he studied computer science and commerce at university before dropping out to drive a taxi.

He left Gambia on August 28, 2012, leaving behind a wife and three children.

After going to neighbouring Senegal, he went to Hong Kong for 14 months before landing in New Zealand.