Detectives hunting Britain's most wanted serial rapist-burglar have obtained more than 2,000 DNA samples from suspects, it emerged today.
Metropolitan Police detectives have undertaken 2,054 tests at a cost of £102,700 as part of a 12-year inquiry to catch a rapist dubbed the "night stalker".
The light-skinned black man targets elderly people and is responsible for more than 100 offences in the south London area dating back to 1990.
A team of 29 police officers and staff based at Lewisham police station continue to work to identify the culprit as part of Operation Minstead.
They have obtained key information about the attacker from forensic samples left at more than 10 crime scenes.
Specialist ancestral analysis revealed both his parents originally came from the Windward Islands in the Caribbean.
As a result investigators drew up a list of 21,500 suspects and began asking men for voluntary DNA samples to eliminate them from the inquiry.
Eight police officers also travelled to the chain of Caribbean islands which include Trinidad, Tobago, St Lucia and St Vincent.
The DNA trawl met some resistance in 2006 after the Met was accused of sending threatening letters to men who refused to take part.
Members of the Metropolitan Police Authority questioned its legality and warned it could inflame community tensions.
The "night stalker" has eluded detectives despite facing a huge range of police tactics, from surveillance to the offer of a £40,000 reward.
The criminal has a distinctive pattern of behaviour, often disabling telephone lines and fuse boxes before breaking into the homes of vulnerable people.
Some of his victims, men and women aged between 68 and 93, have been raped and sexually assaulted.
He often wears a mask and wakes people by shining a torch in their faces. Police said he sometimes spends up to four hours with his victims.
The total number of raids linked to the man during his 19-year reign of terror is now at least 108.
The attacks have taken place in clusters in south and south-east London, including Dulwich, Orpington, Norwood, Downham, Lee, West Wickham and Bickley.
The most recent linked burglaries took place in June, when one of nine break-ins was linked to the suspect by DNA. Two of the burglaries took place in Shirley, Croydon.
The culprit is thought to be an employed black man, aged between 35 and 45, who masks his crimes behind the veneer of a respectable life.
He is believed to be a gerontophile, someone with a sexual fixation with the elderly. Police said the man has raped four people and sexually assaulted 24 others.
:: The number and cost of DNA samples collected as part of the inquiry was revealed after a freedom of information request.