Unconfirmed Australian ­media reports said Gao came to Hong Kong – before he was shot dead in a Sydney warehouse with two bullets to the chest – to ­arrange a 2.78kg consignment of methamphetamine – commonly known as Ice or crystal meth – with senior triads in the city.

Police last night declined to comment on the case which yet again has highlighted the key role organised crime groups in the city play in the multibillion-dollar methamphetamine smuggling business between Hong Kong and Australia.

Since 2006, at least 27 ­Hongkongers have been arrested trying to smuggle HK$15 billion worth of meth into the country. And the amount of the drug seized at Australian ports and airports having arrived from the city is ­almost triple that from the rest of the world.

Gao, who was a student at the University of Technology in Sydney, had been called to give evidence before a secret hearing at the Australian Crime Commission in the weeks before his death.

The commission, the country’s peak intelligence-gathering agency, took the unprecedented step last week of issuing a statement to deny Gao had been acting as one of their informants when he delivered the drugs to Rogerson and McNamara

In addition, two Hong Kong men drove Gao to the deadly drug deal and called New South Wales police 30 hours after he disappeared. They have not been seen or heard from since.

Despite his image as a straight-A student, Gao had been in the sights of the Australian federal police as a suspected drug ­importer for years, according to Australia’s Daily Telegraph.

The clean-cut business student had been a “person of interest” since 2011 and Australian Federal Police had provided a
20-page document to NSW authorities detailing his activities.

Gao’s family issued a statement yesterday which said it was “absolutely fitting” that his killers will die in prison.

The statement said the sentences were “the best outcome we, as Jamie’s family, could have hoped for”.

“To have these two men, who took Jamie from us, sentenced to essentially die in jail, is absolutely fitting,” it continued, adding that they had been given no ­opportunity to present evidence to clear Gao’s name “of the alleged crimes he’s been accused of ­committing”.

In the months after the killing, Australia’s most powerful law ­enforcement agency posted a transnational crime expert to Hong Kong for the first time in an effort to step up the fight against an epidemic of crystal meth, ­primarily sourced from the mainland and routed through Hong Kong.

The first-ever appointment of an investigator from the Australian Crime Commission, which has investigative powers above federal and state bodies, to the Australian consulate in Hong Kong came as the number of seizures of methamphetamine hit record highs in both jurisdictions.

Jeff Gough, who took up a consular position as transnational crime analyst, will be part of the team tasked with dismantling the criminal gangs that supply drugs to the Australian market.