Ripper Hoaxer John Humble was today sentenced to eight years behind bars.

The Recorder of Leeds, Judge Norman Jones QC, told grey-haired Humble he was satisfied one of the features which may have contributed to Sutcliffe remaining at large for so long was Humble's hoaxes.

"You took over his persona, pretending in a series of letters and tapes to be the killer.

"At no time did you have the courage to come forward and confess."

Judge Jones said that three more women were to die at the hands of Sutcliffe and two others were attacked but survived.

He added: "It appears to me you were a man with a disdain and dislike for the police. I believe it gave you pleasure to make fools of them.

"As unforgivable is your failure to put the record straight when you realised the terrible you were doing."

He added: "Had that tape not been sent the deployment to Sunderland, whether wise or not, would simply not have occurred," said Judge Jones.

Earlier Humble's barrister Simon Bourne-Arton QC, in mitigation, said it was not safe to say that Sutcliffe would have been caught a day earlier than he was if Humble had not send the letters and tape.

At this point Judge Jones intervened, saying: "Wasn't one of the bases on which Sutcliffe was discounted by the police was that he hadn't a Sunderland accent?"

Mr Bourne-Arton said this was countered by the fact that several of Sutcliffe's surviving victims described their attacker as having a West Yorkshire accent.

He added that Northumberland Police concluded that over-emphasis was put on the letters and tapes during the Ripper hunt.

The father of a Bradford student murdered by the Yorkshire Ripper today said she probably would still be alive if police had not been fooled by the "Wearside Jack" hoaxer.

Barbara Leach, 20, was battered to death by Peter Sutcliffe only five weeks after detectives ruled him out as a suspect because his handwriting did not match that of the hoax letter writer.

At Leeds Crown Court yesterday, former window cleaner Humble, 50, pleaded guilty to four counts of perverting the course of justice after admitting he was the man who took in police chief George Oldfield and his Ripper Squad.

Humble sent the taunting "I'm Jack" tape and two letters, in which he claimed to be the Ripper, to Assistant Chief Constable Oldfield, and a third letter to a national newspaper.

The hoaxer was so convincing the focus of the police investigation turned to the North-East, diverting attention from the real Ripper, after which he killed three more women and carried out two other attacks.

Detective Constables Andy Laptew and Graham Greenwood carried out the fifth interview with potential suspect Sutcliffe on July 29, 1979, and failed to be satisfied he was innocent.

They filed a two-page report detailing their suspicions and saying the Bradford lorry driver should be investigated further.

But, because of the letters and the tape, Sutcliffe was cleared on the basis of a handwriting specimen. No further action was taken and the report was marked "to file." At 1am, on Sunday, September 2, 1979, Barbara Leach became the 11th murder victim of Sutcliffe when he attacked her just outside Bradford city centre.

Barbara, who was about to start the final year of her social psychology degree course at the university, was having a walk after enjoying a drink with friends when the Ripper pounced in Ash Grove, near to the university.

He attacked her from behind with a hammer, dragged her into a backyard and stabbed her with a screwdriver - which he had used in the murder of Josephine Whitaker five months earlier. He then placed her body behind a low wall, covered it with a piece of old carpet and placed some stones on top of it.

Sutcliffe also went on to murder Marguerite Walls and Jackie Hill, both in Leeds, before he was finally caught.

Barbara's father, David Leach, said it was a "pity" the police had been so "obsessed" with the hoaxer when the investigation was going on.

Mr Leach, who lives with his wife Beryl in Kettering, Northants, said: "The letters and tape were crucial to the whole inquiry and it's true that they changed the focus of the investigation.

"It meant that if a suspect didn't have a North-Eastern accent they would not be seen as a suspect by the police. Barbara would probably still be alive if the hoax letters and tape had not been sent."

Mr Leach said that Humble was more at fault than the police because he had started the misleading line of inquiry.

He added: "I hope he is sent to jail for a long time for what he has done. He has caused a lot of grief to a number of people."

Yesterday Humble sat in the dock with his head bowed as his chilling "I'm Jack" tape was played to a packed courtroom.

In a dramatic development just before his trial was set to start he had pleaded guilty to all four charges of doing an act tending and intended to pervert the course of justice.

He admitted sending two letters to Assistant Chief Constable of West Yorkshire George Oldfield and a third to the Daily Mirror in Manchester claiming he was the Yorkshire Ripper.

He also admitted sending the notorious tape to Mr Oldfield on June 18 1979.

Humble, who is grey-haired and has a moustache, was wearing a royal blue sweatshirt.

Prosecutor Paul Worsley QC said that Humble sent the letters and tape to deliberately obstruct police hunting for the Yorkshire Ripper between 1975 and 1979.

"The Ripper, we submit, must have been well pleased," said Mr Worsley.

He said that after Sutcliffe's arrest in January 1981 he told detectives: "While ever that was going on, I felt safe. I am not a Geordie, I was born in Shipley."

Mr Worsley said that after Sutcliffe was sentenced his trial judge Mr Justice Boreham said the case must have been a nightmare for West Yorkshire Police. The judge said the scent had been falsified by a "cynical, almost inhuman hoaxer".

Mr Justice Boreham said that it was his hope and that of almost every member of the public that he might one day be exposed.

Mr Worsley said the first letter was sent by Humble after the murder of 16-year-old Jane MacDonald in Leeds. Sutcliffe was already in the frame as the Ripper suspect and had been interviewed by detectives.

By this time eight women had been murdered.

Five days later Humble sent another letter, this time to the Daily Mirror, in which he stated: "Might write again after another one's gone."

Mr Worsley said that after a press article in February 1979, Humble would have realised that police were taking the letters seriously. "His reaction - it was to write again," he said.

Ten women had been murdered by the time Humble sent his third letter on March 23, 1979.

The chilling audio tape followed on June 18 of that year.

Mr Worsley said the three-minute message had been read to a script, the words chosen painstakingly and the speech measured without hesitation or mistake. There was no background noise to give any clue. "It was a haunting and a sinister recording," he said.

"The hoaxer knew that the police could not disregard the tape. Who else but the Yorkshire Ripper himself would convincingly want to throw the police off the scent of the killer," said Mr Worsley.

The court was shown a recording of the national ITN news on June 26, 1979 in which it was stated: "Police are convinced the voice is that of the Ripper."

Mr Worsley said that later that year Humble made a suicide bid by jumping of the Wearmouth Bridge in Sunderland but he was rescued by police officers.

By November 1980 13 women had been murdered and Sutcliffe was caught only by chance on January 2, 1981 when he was arrested on suspicion of theft.

Mr Worsley said Humble had amassed an "encyclopaedic knowledge" of Sutcliffe's activities and words and phrases he used were similar to those used by the original Jack the Ripper in his letters to police the century before.

Mr Worsley said that Humble did ring the police in September 1979 to say that the tape was a fake. He made the call to an incident room in Sunderland and said he followed it up by another call to officers in Bradford.

It had cost £6 million to investigate the Sunderland letter and tape.

"It was all for nothing. All because one man had set out to pervert the course of justice," said Mr Worsley.

After his arrest Humble refused to speak to officers so that they could not hear his voice. After that he admitted he was the hoaxer.

He told officers he wanted to "boost up the hunt" because he was bored and on the dole. He said he was probably drunk at the time.

"I shouldn't have done it because it was evil. I was on the dole. I had nowt to do. I regretted it after," he said.

Humble was due to be sentenced today by Recorder of Leeds, Judge Norman Jones QC.