Investigators tracking the Night Stalker used cutting-edge techniques to try to build a picture of the man from his DNA.
Several samples were recovered from attacks but because Delroy Grant was not on the DNA database police could never identify him.
This was despite the fact he had a significant criminal history, with convictions including attempted robbery and handling stolen goods.
As a result, police turned to a company based in Florida to help them build a picture of their suspect's ancestry.
The value of the expensive lab work and analysis remains disputed, even among detectives.
Scientists found Grant was of Caribbean origin and further work claimed his ancestors probably came from the Windward Islands.
After his arrest, police found Grant was Jamaican and have yet to find any links to the Windward Islands.
Eight police officers travelled to the chain of Caribbean islands, which include Trinidad, Tobago, St Lucia and St Vincent, as part of the inquiry.
Detective Superintendent Simon Morgan, who led the inquiry from 2001, said police focused on the DNA as victims gave limited and conflicting descriptions of Grant.
He said: "We kept up to pace with the world of science and technology that was developing DNA analysis and looked at what this could tell us about this offender.
"A sample was sent to Florida for ancestral analysis. The results were blind tested by experts in the UK. At the time, a limited number of experts existed in the world.
"They agreed that the interpretation of the analysis that his ancestry from five generations previously was Caribbean.
"This was effectively the time of the America slave trade. A mathematical presumption was that his ancestors were from the Windward Islands in the southern Caribbean.
"We now know he was born in Jamaica but we do not know his ancestry. The benefit of this ancestral work is that we were able to rule out thousands of individuals of African origin that were clearly not our priority."
Meanwhile, a move to collect DNA samples from more than 3,000 suspects sparked controversy and resentment among the black community.
Senior officers later admitted that the voluntary DNA testing did little to further the inquiry as 5,200 potential suspects remained on the system.
As the investigation went on police were swamped with information as they amassed details of 27,000 people on their database.
Police saw a similar lack of success with a steady stream of profilers and criminal psychologists brought in to give an insight into his lifestyle.