McCormick called his invention ADE 651, for "Advanced Detection Equipment", but there was nothing hi-tech about it, British police who led the "long and complex investigation" said.

Detective Inspector Edward Heath, from Avon and Somerset police, told the that the device had no electrical component and was "literally" a swinging metal stick on a handle that moved simply with gravity.

"There's nothing in any laws of science that could say these devices could ever work," Heath said.

The court testimonies of electronics experts demystified McCormick's product claims, he said.

McCormick, 57, worked out of Somerset, southwest England, primarily marketing the device as a bomb detector that accurately pinpointed the presence of any type of explosive using a special card. There were different cards for different targets - cocaine or bombs, for instance.

Based on the idea of a golf-ball finder, it was touted as the deterrent of choice for countries looking to tackle serious problems.

And people trusted James McCormick, himself a one-time police officer.

His brief insight into the workings of law enforcement gave him the confidence to be a lawbreaker. Banking on the trust he engendered, he took advantage of people and governments.

Hong Kong is not alone in being fooled; the United Nations was sold the device, as were 24 countries including Niger in West Africa, Saudi Arabia and Belgium.

In Iraq, the ADE became a staple weapon for local forces combating terrorism.

From duping people into buying the supposed bomb and drug detectors, McCormick's company netted £60 million (HK$703 million) over a 13-year period. The fraudster spent his ill-gotten gains buying real estate in Florida and Cyprus. He also owns a HK$61 million townhouse in Britain.

However, Heath said police believed his actual earnings could be a less generous HK$93 million after bribing "corrupt officials and hence he hasn't made more money".

It was bribery, Heath said, which started this lucrative business based on lies. Iraq alone bought 6,000 devices.

Conman McCormick's sales patter was honed down to perfection, marketing an invention to "protect life, limb and property", police said, and he had an excuse ready if things did not go according to plan.

If the device failed to find anything, McCormick said the user had not been trained properly; if the metal stick pointed to an area with no drugs or explosives, he said it had detected traces of what used to be there.

His web of deceit started to unravel when American and British military officers in Iraq noticed the unfamiliar devices at Iraqi checkpoints. The "Made in the UK" claim was a giveaway that warranted further inquiries and expert tests to determine its technology.

In December 2009, British police launched an investigation.

To date, Avon and Somerset police are still raising concerns that the device remains in use around the world.

More seriously, police suspect - but were unable to prove in court - that the ADE had a direct link to deaths of many innocent and helpless people who used the device for crime-fighting.

In the 25 years of Heath's career, the scale of deception was nothing short of "breathtaking", he said. "It's the largest financial case I've ever experienced and I've been in the police for 25 years and this surpasses it all," he said.

Heath said it would take about two years to unwind and liquidate McCormick's assets - but his victims and clients, including the Hong Kong Correctional Services Department, were unlikely to get their money back.