Night Stalker found guilty – after 17 years and up to 500 victims

A former mini-cab driver believed to be Britain's most prolific sex attacker was found guilty yesterday of conducting a 17-year reign of terror against elderly women and men.

Delroy Grant, 53, known as "Night Stalker" because he broke into his victims' homes after dark wearing a mask, before subjecting them to terrifying ordeals, sometimes lasting several hours, was warned he faces a "very long sentence" by the judge at Woolwich Crown Court, in south-east London.

Although he was convicted of burgling and assaulting 18 pensioners between 1992 and 2009 across south London, Surrey and Kent, in what police said were some of the most shocking and callous crimes ever investigated by its officers, detectives believe he may have struck up to 500 times. The attacks, including four rapes and 20 sexual assaults, were described by prosecutors as "the stuff of nightmares".

Yesterday Scotland Yard was forced to apologise for a series of blunders during the long investigation, which was one of the most complex in the force's history, cost tens of millions of pounds and involved hundreds of officers. It emerged that a mix-up over the suspect's name had resulted in Grant being eliminated from the inquiry 10 years before he was eventually caught. Police had also failed to investigate after receiving a tip-off naming him.

The Independent Police Complaints Commission (IPCC) criticised the Met for "basic errors", which it said had "horrific consequences". Senior officers are expected to give the go-ahead to a major inquiry in the aftermath of yesterday's conviction. Investigators have visited 203 surviving victims to brief them on the progress of the prosecution. It also emerged that they have been contacted by the families of two rape victims who only came forward after they died.

Grant stood in the dock with his head bowed as the jury foreman delivered the majority verdicts after more than eight hours of deliberation. Judge Peter Rook said Grant had been convicted of 29 offences "of the utmost gravity", but delayed sentencing until today when more of his victims could give evidence on the impact of the crimes.

Among those he attacked was an 89-year-old woman; others were blind, deaf or had conditions such as Alzheimer's or Parkinson's. All the victims were vulnerable and living on their own within driving distance of Grant's home in Brockley, south-east London.

Grant targeted 1930s houses in leafy commuter suburbs, often levering out window units with a crowbar to gain entry. He would remove light bulbs and cut phone lines to evade detection and once inside would often talk to his victims. Police said he was a skilled burglar who would carefully select his targets and cover up his DNA traces.

The offences took place in areas including Warlingham, Beckenham, Bromley, Addiscombe, Orpington and West Dulwich. He was caught in 2009 during a 16-night police surveillance operation in Shirley.

After his arrest Grant, a father of eight children by four different women, suggested that detectives talk to his son, whom he said was the possible culprit. He then claimed that his ex-wife had been framing him with body fluids she had asked for from him in 1979. During the trial Jonathan Laidlaw QC, prosecuting, described Grant's defence as "utter, utter rubbish".

Andrew Hadik, a senior Crown Prosecution Service lawyer, condemned Grant for refusing to face up to his depraved actions. 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."