The man who hoaxed detectives by claiming to be the Yorkshire Ripper has died, police have confirmed.
John Humble, who was dubbed Wearside Jack, sent police on a wild goose chase when he sent them hoax letters and an audio tape in the late 1970s.
Northumbria Police said Humble, who had changed his name to John Samuel Anderson, died on 30 July.
West Yorkshire Police detectives, headed by the force's assistant chief constable George Oldfield, believed the letters and tape were genuine and diverted resources to Humble's home town of Sunderland.
When Humble was eventually prosecuted, Leeds Crown Court heard claims that delays caused by the hoax allowed Peter Sutcliffe to murder three more women.
Sutcliffe was jailed in 1981 and given 20 life sentences for killing 13 women and attempting to kill seven more.
Humble, 63, died at his home in South Shields, where he had lived since being released from prison in 2009.
A force spokesman said his death was not being treated as suspicious and would not be investigated.
The former labourer later admitted writing two letters and recording the audio tape and sending them to police between 1 March 1978 and 30 June 1979.
He also sent a third letter to the Daily Mirror newspaper.
Humble was said to have had a fascination with the original Jack the Ripper, who terrorised the streets of east London in 1888.
A spokeswoman for South Tyneside coroners office said no inquest had been held into Humble's death, which was reported to the borough's registrar by a member of his family.
"I remember listening to it and being incredibly puzzled because there was nothing on the tape that actually suggested it was genuine".— The World at One (@BBCWorldatOne) August 20, 2019
Journalist Joan Smith @polblonde on the death of Yorkshire Ripper hoaxer "Wearside Jack". #bbcwato https://t.co/G8tounUAyc pic.twitter.com/RNZVLnM62o
West Yorkshire Police declined to comment, but former Det Supt Bob Bridgestock, who was part of the Ripper squad, said lives "could have been saved" were it not for the hoax.
He said: "We don't know what Humble's reasons were for doing what he did.
"But he really frustrated, hindered and distracted the inquiry.
"After the tape there were another three women killed. Perhaps lives could have been saved if it hadn't been for him."
Sutcliffe, from Bradford, is currently serving life at Frankland Prison, in County Durham.