Mr Bradfield was the prime suspect in the murder of James Gaspa, who was shot dead at his home in Islington, north London, in May 2000.
Police were about to issue an extradition warrant for him and it is possible he was killed to prevent him turning supergrass.
But he may have been executed simply because his dealing had encroached on a rival's territory.
The drugs trade and the property boom are luring criminals of all nationalities to the Costa del Sol.
Deborah Johnson - not her real name - is a British estate agent who works on the coast.
She said there was a degree of "no questions asked" when foreigners bought property, often in cash.
"We had a lot of cash buys just before the euro came in," she said.
Police said they feared criminals would try to launder money in old European currencies to avoid having to exchange it for euros and in the process declare it.