Scotland Yard has been forced to apologise for bungling another high profile manhunt after admitting one of Britain's most depraved sex attackers should have been stopped a decade earlier.
Hundreds of elderly victims are feared to have been preyed on by Night Stalker Delroy Grant after officers botched a chance to arrest him in 1999.
As the 53-year-old former minicab driver was convicted of a 17-year campaign of perverted terror today, the Met was criticised by its watchdog for "basic errors" which had "horrific consequences".
It is the latest in a string of controversies to tarnish the force's record on snaring sex attackers.
Officers previously said sorry for failing to link a string of attacks to rapist cabbie John Worboys and also admitted they should have arrested children's football coach Kirk Reid earlier for stalking and attacking women.
Detectives fear Grant attacked more than 500 elderly people during some of the most "awful and disturbing crimes" ever investigated by the force.
Commander Simon Foy, head of the Metropolitan Police's homicide and serious crime command, said Grant's conviction lifted a shadow of fear from thousands of pensioners living in south London.
But he apologised for the paperwork blunder which led to the DNA of another suspect scuppering attempts to snare the sex beast.
"We are deeply sorry for the trauma suffered by all those victims and our failure to bring Grant to justice earlier," he said.
Twice-married Grant has been told he could face a life sentence for his sickening and depraved attacks.
One elderly victim smiled while a police family liaison officer looked on in tears of relief as the jury at Woolwich Crown Court found him guilty of degrading attacks on 18 frail pensioners across south London.
Grant stood motionless in the dock with his hands clasped throughout as the verdict was returned after eight-and-a-half hours' deliberations.
Judge Peter Rook QC told him: "You have been convicted of 29 offences of the utmost gravity."
Grant is a "perverted, callous and violent individual" who attacked some of the most vulnerable people in society, Commander Foy said.
Between 1992 and 2009 the masked sexual predator preyed on frail men and women and violated them in their homes, sometimes for several hours.
Many of his victims - aged up to 89 - were blind, deaf or had conditions including Alzheimer's and Parkinson's disease.
Grant targeted detached and semi-detached 1930s houses in leafy suburbs, often levering out double-glazed window units with a crowbar to gain entry.
He was a highly-skilled burglar who carried out daytime reconnaissance.
The hallmark of many of his offences was to remove light bulbs, cut telephone lines, then grab his victims with a gloved hand.
He woke terrified pensioners by shining a torch in their eyes before engaging them in conversation.
Grant then subjected his vulnerable victims to humiliating and degrading sexual assaults for a gratification described in court as impossible to understand.
His "stuff of nightmares" crime spree sparked an international manhunt by police.
Officers had been hunting the Night Stalker, under the codename Operation Minstead, since 1998 when two rapes were linked to the same attacker.
Grant, of Brockley Mews, Honor Oak, eluded capture for years as the tally of victims linked to Minstead soared to 203. The offences took place in areas including Warlingham, Shirley, Beckenham, Bromley, Addiscombe, Orpington and West Dulwich.
The sex beast's luck finally ran out when police swooped on his car in the early hours of November 15 2009.
More than 70 undercover officers, supported by hidden cameras and a helicopter, staked out several streets in Shirley, near Croydon, in an ambitious operation after Commissioner Sir Paul Stephenson called for a "step change" in the hunt.
Grant, a father of 10 and full-time carer for his estranged wife Jennifer, who has multiple sclerosis, refused to discuss his crimes with police.
But he stunned officers by suggesting they should instead speak to his son.
By the time the case arrived in court more than a year later, he had spun a web of lies in an attempt to get off the hook.
Among a string of "almost laughable" explanations at Woolwich was his claim that his ex-wife stored his semen in 1977, then waited 15 years to frame him for the crimes.
Andrew Hadik, a senior Crown Prosecution Service lawyer, condemned Grant for refusing to face up to his crimes.
He said: "We may never know exactly why Delroy Grant raped and attacked so many innocent people over the last 17 years - he has steadfastly refused to admit any responsibility or to show any remorse.
"His vicious attacks, masked with a contemptuous politeness towards his victims, traumatised people who should have been enjoying the security and comfort of their own homes."