The case is unusual because New Zealand-based crime syndicates usually focus on trafficking drugs into the country, not in reverse.
Da'Silva spent two days in Dubai, which is a known transit point for organised crime groups in neighbouring Iran to send methamphetamine and other narcotics around the globe.
He was also booked to spend two days in Dubai on his flight home to New Zealand, raising the possibility of an attempt to bring more P into the country where the street price is much higher than in the United Kingdom.
The 4kg he was caught with was estimated by the Border Agency to have a street value of $1.5 million. The same amount is worth $4 million in New Zealand.
Da'Silva was arrested after a white powder was discovered leaking from the broken handle of one of his bags.
Subsequent x-rays of his luggage revealed the drug inside various electronic items, including a Sony PlayStation and a laptop computer.
Da'Silva, discharged as a bankrupt in November last year, was supposed to enjoy a week at a 5-star luxury resort in Fiji on his return from New Zealand. Instead, he will serve five years and then be deported.
Dubai has also featured in a recent drug case in Auckland. Polish man Adam Tyniec flew to Auckland International Airport on an Emirates flight from Dubai in April last year.
Nearly 2kg of P was found when his suitcase was x-rayed.
Tyniec, 50, later told authorities he refused the advances of the Iranian syndicate on a number of occasions and was "stupid" for yielding.
A covert investigation later arrested Yashar Ghasemi, a 33-year-old who came to New Zealand as a refugee, after he took control of the package.
He was sentenced to nine years in prison after pleading guilty to possession for supply, as well as supplying methamphetamine.
Bought for as little as $5000 in Iran, 1kg of methamphetamine can be sold in ounce bags (28.5g) for nearly $500,000 at wholesale prices in New Zealand.
A kilogram of P is worth $1 million at street level.
Cash can be moved around the world through an Islamic money transfer scheme, hawala, which police say makes it virtually impossible to trace money laundering.
Syndicate mule
Paul John Domingo Da'Silva
*57-year-old from the North Shore.
*Caught with 4kg of methamphetamine at Heathrow.
*Pleaded guilty and jailed for 5 years.
