A tiny piece of gum from an envelope put Yorkshire Ripper hoaxer John Humble behind bars, more than 25 years after he committed the "unsolved crime of the century".

The taunting tapes and letters which sent Ripper Squad police on the wrong trail, while evil Peter Sutcliffe carried on his killing spree, were destroyed years ago.

But a quick-witted scientist chose to hang on to the scrap of gum sealant used by Humble to send one of his misleading letters to police.

As reported in later editions of the T&A, shambolic alcoholic Humble was yesterday jailed for eight years after the gum provided the DNA evidence to link him to the sinister crimes.

The Recorder of Leeds, Judge Norman Jones, QC, told the 50-year-old former window cleaner he had used his knowledge of the original Whitechapel Jack the Ripper to create his own persona of the Yorkshire Ripper.

He even copied the language of Jack's original letters to send the police team "taunts and boasts, coupled with threats of further acts", the judge said.

He told Humble: "They were well researched to persuade police you were the killer. Then you sent to the chief investigating officer a tape with you pretending to be the Ripper. It was a cleverly contrived tape, with the words written out before, and was sinister, flat and ominous."

The judge said Humble had intended to "manipulate the justice system and produce injustice".

He told him he had bent the investigation into "one of the most horrific series of murders ever in this country" away from the true killer.

Judge Jones added: "You did that with indifference to the potential consequences."

Humble remained emotionless with his hands clasped behind his back in the dock before he was led away to start his sentence.

The mother of Bradford student Barbara Leach, who was murdered by Sutcliffe after the hoax tape and letters were sent, welcomed the "severe sentence". Beryl Leach, 74, of Kettering, Northants, said: "I did not expect it to be quite as hard. I had hoped for five years. I am glad it was eight years. It will give him time to reflect.

"I was beside myself with anger when I saw him on television. I wanted to lash out at him. It made me very angry for what he did. It brings back bad memories."

Mrs Leach said she was astounded Humble had told police after he was arrested he had written the letters and made the tape because he was "bored and hated police".

She added: "It's beyond belief. I hope now this is the end of it. I honestly do not know what Barbara would have thought.

"We keep our nice memories of her. I still miss her. We always think if we have flowers they are for her. I have flowers in the house by her photo."

Detective Chief Super-intendent Chris Gregg, head of West Yorkshire Police's Homicide and Major Enquiry Team (HMET), said Humble had conducted a "calculated campaign," drawing his information from the media, and had kept his crimes to himself over the years.

He said the case had never been closed and West Yorkshire Police had carried out two reviews. It was looked at again when the HMET was formed.

Det Chief Supt Gregg said: "We knew this was unresolved. If there was an opportunity to find out who was responsible we would take it. It started out as a long shot, but it was worth it.

"I worked on the original inquiry as a young policeman and to be at this end of it now is quite remarkable. It all fell into place far better than we could have hoped."

He added: "Whilst the person responsible for the hoax letters and tape was unknown it left a great number of people connected to victims of the Yorkshire Ripper with unanswered questions.

"Today we have the benefit of modern-day science which our colleagues in the past did not have. It's only right we take full advantage of every aspect of cutting-edge science when reviewing unsolved cases.

"It's impossible to quantify the effect that the Yorkshire Ripper case had on a great many people. Identifying John Humble as the man responsible for misdirecting the police investigation is an important step in bringing closure to that unresolved part of the investigation."

Richard Hebbert, senior crown prosecutor for the Crown Prosecution Service, said they had always been convinced it was a meticulously researched and carefully planned campaign deliberately aimed at misleading the police and played a significant part in enabling Peter Sutcliffe to evade detection for a further two years.

He added: "Even when Humble realised his claims were taken seriously he continued with the charade.

"It was clear to him the focus of the investigation had moved as a direct result of his communications but he still failed to make any serious attempt to alert West York-shire Police it was a hoax."

Richard McCann, son of Sutcliffe's first murder victim, Wilma McCann, said: "Up until yesterday, every time I heard that tape played I thought of Peter Sutcliffe. Now I think of John Humble. I have some closure there."