Standen's dramatic arrest was the culmination of an investigation spanning four continents that dismantled a large drugs syndicate.

As assistant director of the New South Wales Crime Commission, he led the investigations of a powerful agency tasked with tackling major drug traffickers, organised crime networks and corrupt cops.

But prosecutors say their prime suspect crossed the fence, and he is now accused of co-ordinating a plot to flood Australia with A$120 million (HK$895.54 million) worth of the drug Ice.

The charges have cast a pall over the 30-year career of an officer who led major busts and had regular access to the most sensitive intelligence material.

Among many detectives in Sydney's tight-knit law enforcement community, Standen had long been regarded as something of a legend. Elsewhere in the ranks, suspicion lingered that he was bent.

Those with long enough memories recall corruption charges laid in 1982 against the young agent when he was employed by the now-defunct Federal Narcotics Bureau.

Standen and his partner, Stephen Innsley, allegedly failed to report the seizure of 18 foils of cannabis and were caught flushing them down a toilet.

The charges were dropped on the understanding that the pair would not get jobs with the newly formed Australian Federal Police, but Standen was duly appointed. He soon forged a tough reputation and was highly respected.

Yet 12 years ago colleagues were shocked when he volunteered for redundancy. And last week it was reported that the majority of his six-figure payout was used to cover substantial betting losses.

Later, after he had joined the Crime Commission, the family home was remortgaged to finance debts to bookmakers understood to have surpassed A$1 million.

In the spectacular fallout from last week's arrest, much has been made of Standen's gambling problem and the fact it was well known in police circles for years.

'This is the sort of stuff that should have raised alarm bells instantly, that one of [the commission's] investigators was in a vulnerable position,' said one law enforcement official. 'But the checks and balances seem to have failed.'

While sources close to the Ice investigation have played down the relevance of his addiction and financial woes, they are in no doubt that he was a pivotal player in the alleged plot.

It was June 2006 when Australian authorities were initially tipped off by Dutch police about plans to ship 600kg of ephedrine Down Under.

The chemical is a key component in the manufacture of illegal drugs such as Ice and Ecstasy, and started its long journey as legitimate medical aid intended for the Congo. But, like so many consignments, it was redirected by corrupt officials to a European-based drug syndicate which satisfies a lucrative demand for illegal drugs around the globe.

The key to the Australian plot was alleged middleman James Henry Kinch, a convicted British criminal and nightclub owner in Portugal.

Federal agents monitoring his conversations were astonished when he got a phone call from Standen.

At first they thought the detective might have been conducting his own - legitimate - operation. It is believed Kinch had previously worked for Standen as an informant. Within weeks, however, it was apparent that Standen was being driven purely by personal gain.

An unprecedented round-the-clock surveillance operation was set up, tracking every move of Standen and his alleged co-conspirator, food importer Bill Jalalaty. The pair had met through Jalalaty's wife, Dianne, who worked with Standen.

Their plan was allegedly hatched in January last year when the two suspects met Kinch in Dubai. Standen, a married father of three, was accompanied by his mistress Louise Baker, who also worked at the Crime Commission.

Hundreds of phone calls and e-mails were monitored and meetings bugged as investigators built up a precise picture of the attempt to smuggle the chemical haul in a shipment of basmati rice.

Prosecutors will allege Standen used his official credentials to seek detailed information on security at Sydney's main container port, and advised the drug syndicate on the best ways to avoid detection.

Other aspects of the operation, which found their way into Australian newspapers last week, appear amateurish by comparison.

The Daily Telegraph in Sydney reported that Standen used a personal e-mail address and office fax to communicate with Kinch. When the three men talked about the drugs, they used a simple code referring to their children and toys. Standen was also heard criticising Jalalaty's idea of using a hosiery company to import the 'rice', suggesting it would attract unwanted attention.

In a bizarre twist, police believe the pair lost more than A$1 million lent by the Dutch syndicate to set up the Australian end of the deal. Jalalaty allegedly gave the money to a clairvoyant who had promised huge returns, but the money disappeared.

Standen put him in touch with Frank Wheeler, an imposing figure who specialised in debt recovery. Wheeler told the Telegraph he traced the cash to the Bahamas but Jalalaty could not afford the A$50,000 to 'take the boys' there to retrieve it.

Two trial shipments are understood to have reached Sydney, and the police tapes capture a range of emotions from both men as the plot headed towards its conclusion.

In January Standen was heard describing how importing drugs was not what he wanted to do, but 'the reality is, someone else would be doing it and rolling in the money so we might as well get a benefit'.

To help keep the surveillance operation secret, only a handful of senior police personnel were told.

The investigation also relied on close liaison between law enforcement agencies in the Netherlands, Germany, the United Arab Emirates, Thailand and Pakistan. But most interest centred on the alleged involvement of such a high-ranking detective, and those involved remain surprised that Standen - no slouch in counter-surveillance techniques - never realised he was under scrutiny.

The consequences have been spectacular.

Dutch police, who arrested 12 suspects in a series of raids, believe they have smashed a major drugs ring. In Sydney, Standen and Jalalaty have been charged with conspiring to import precursor chemicals, supply of a large commercial quantity of illegal drugs and perverting justice. They face a maximum penalty of life in prison Kinch was arrested in Bangkok as he prepared to board a flight to Germany, and now faces extradition to Australia.

There has also been focus on Standen's mistress, Baker, who worked at the Crime Commission and accompanied him on his trip to Dubai in January.

Several weeks later she was transferred to the New South Wales Independent Commission Against Corruption following a request by Crime Commission boss Phillip Bradley, who cited an affair with an unnamed officer. The police say she is not a suspect.

Standen's arrest has also brought to a head concerns over the powers and lack of accountability at the agency he worked for. Mr Bradley is a potent symbol of its secretive nature.

Last week's appearance in front of the media was his first in almost 20 years in charge.

Bowing to pressure, the New South Wales government has said that the body which oversees the state's police force will now take on the same role with the commission.

There are still calls for a judicial inquiry into its operations, and speculation that the arrest could have implications for a number of commission cases still before the courts.

Questions have also been raised about investigations involving Standen, including one operation in which police allowed 7kg of cocaine to be sold on the streets in a botched attempt to catch dealers - and recovered only 1kg.

Some legal experts believe the Crime Commission will be fortunate to survive the bloodletting.

Standen, meanwhile, is pondering a bleak future, isolated from other prisoners in a maximum security jail for his own safety. There have been reports that that main shipment bound for Australia was unloaded in Pakistan by double-crossing criminals.

This week Standen will apply for bail. 'He's obviously stressed and upset about the whole thing,' said his lawyer, Paul King. 'I think it's all taken him by surprise.'