Delroy Grant was found guilty at Woolwich Crown Court of 29 counts of preying on 18 elderly men and women.
Police fear the 53-year-old may have attacked as many as 500 vulnerable people in what detectives described as one of the most “awful and disturbing crimes” ever investigated by Scotland Yard.
Detectives publicly apologized for missed chances to apprehend Grant as an investigation by police watchdog, the Independent Police Complaints Commission (IPCC), found that basic policing errors led to his not being caught sooner.
Deborah Glass, IPCC commissioner for London, said: “It is clear that a simple misunderstanding had horrific consequences. Police missed the opportunity because confusion led to the wrong man’s DNA being compared.”
Grant was convicted of raping an 89-year-old woman after breaking into her south London home in 1992, the Press Association reported.
He also carried out a brutal sex attack on an 81-year-old woman in Warlingham in 1998, the jury ruled.
Between 1992 and 2009 the masked sexual predator preyed on frail men and women in south London and violated them in their homes, sometimes for several hours.
Grant of Honor Oak, south London, carried out attacks in Warlingham, Shirley, Beckenham, Bromley, Addiscombe, Orpington and West Dulwich.
Many of his victims — aged up to 89 — were blind, deaf or suffered from illnesses including Alzheimer’s and Parkinson’s dizease.
He woke terrified pensioners by shining a torch in their eyes before engaging them in conversation, the court heard.
Judge Peter Rook described his 17-year campaign as “sickening and depraved,” while Jonathan Laidlaw prosecuting said the series of attacks “really is the stuff of nightmares.”
The Jehovah’s Witness went to great lengths to avoid capture as a nationwide manhunt to catch him gathered pace, the court heard.
After his eventual arrest in 2009, the jury heard he tried to frame his own son and then even said his ex-wife, Janet Watson, set him up.
Grant’s claims that Watson “fitted him up” by storing his semen in 1977 “simply defies belief,” Laidlaw told the court.
