In China, drug trafficking convictions carry the death penalty. Gardner could be sentenced to death by firing squad if convicted.
Australian media reported that Ms Davis was released due to behind-the-scenes diplomacy and lobbying by Australian officials with their Chinese counterparts.
Consular assistance
But a Ministry of Foreign Affairs and Trade (Mfat) spokesman in New Zealand said the decision to release Ms Davis was China's alone, and was not dictated by which government had lobbied Chinese officials harder.
"We understand the decision to release Ms Davis rested solely with Chinese authorities. The Australian Government has advised that no negotiations were held to secure Ms Davis release, neither by consular officials nor by Foreign Minister Julie Bishop."
It is understood Ms Davis was travelling with just hand luggage at the time of her arrest, which may have aided her case as the drugs were believed to have hidden in check-in luggage, according to Australian media.
Did secret negotiations secure her release? Kalynda Davis. Photo / Supplied
The Mfat spokesman said the ministry could not comment further on the ongoing investigation "or interfere in the judicial proceedings of another country".
Mfat said Gardner had been given assistance by the New Zealand Consulate-General in Guangzhou. "The Consul-General has visited Mr Gardner in the detention centre to check on his well-being. He has legal representation."
The Sydney Morning Herald said Ms Davis's parents, Larry and Jenny Davis, had hired lawyers in Sydney and China to secure her return. They praised Chinese officials for their "professional and honourable investigation".
They said that they were praying for Gardner's return. "To the family of Mr Peter Gardner, we will continue to pray for Peter and your family. You are always in our thoughts."
The Sydney Morning Herald described Ms Davis as a gifted basketball player and former private school student. It said her father worked at ANZ and had previously been a police officer.
Praise for China
Ms Davis' friend Blayke Tatafu was relieved to see her back in Australia. "Everyone is surprised at the outcome, but not surprised that the truth came out the way it did," he told AAP. "I always said I didn't think she could do something like this."
Ms Davis' parents thanked Australian authorities for negotiating with the Chinese government and authorities. They also commended Chinese authorities for their "professional and honourable" investigation of the case.
Sydney's Daily Telegraph reported that Australian consular officials spent more than three weeks in China in intense negotiations to try and prove Kalynda Davis was not aware of the A$80 million (NZ$86.3 million) package.
Australian Foreign Minister Julie Bishop was overseeing the negotiations, keeping them strictly under wraps so as not to jeopardise the sensitive talks, which also involved local and Chinese lawyers.
Ministers were told on a need-to-know basis amid fears that bad publicity could sabotage negotiations.
Officials from the Department of Foreign Affairs were convinced they had a chance at saving Ms Davis, but understood the fragility of the situation. Ms Bishop was kept informed the whole time.
A family liaison - Dfat's Claire Went - was sent from Canberra to China to support the Davis family, who said in a statement they would not have made it through without her.
"Without the support of Ms Went we would not have been able to get through this difficult time," they said.
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- AAP, Mail Online and nzherald.co.nz
