POLICE have lost the original audio tape and letters from "Wearside Jack", the elaborate hoaxer who claimed to be the Yorkshire Ripper.

Peter Sutcliffe remained at large for months and killed three more victims, largely because West Yorkshire Police fell victim to the hoax which switched their murder hunt from Yorkshire to Wearside and cost £4m.

But a force spokeswoman has said that the original tape and letters - which prompted the biggest wild-goose chase in British criminal history - cannot be found.

She said: ''There's currently an audit under way and at the moment we have been unable to find the original letters or tape.

''There is no evidence that they have been stolen or disposed of maliciously or anything - we just can't locate the items.

''The audit has been taking place for the last 12 months and it's as a result of that that we realised they were missing.

''There was that much stuff. Some stuff, particularly with old inquiries, goes to the CPS (Crown Prosecution Service) and to storage in London.

''We're going to have to check all our storage locations before we can say we definitely don't have them any more.''

She said she could not say how long that would take.

Sutcliffe was jailed for life in May 1981 after admitting murdering 13 women and the attempted murder of seven others between 1978 and 1980.

The bizarre tape was first broadcast nationally on June 26, 1979 - more than 26 years ago - and sent police on the biggest wild-goose chase in British criminal history.

West Yorkshire Police Assistant Chief Constable George Oldfield was convinced the taunting tape and letters were sent by the Yorkshire Ripper and channelled his resources into finding a Wearside man.

Sutcliffe himself was questioned several times by detectives during the inquiry, but released because he had a Bradford accent and Mr Oldfield was convinced the Wearside hoaxer was the Ripper.

That hoax, for which no-one was ever caught, cost more than £4m and years of painstaking police work.

Sutcliffe himself later said the hoax was ''divine intervention'' which left him free to kill his last three victims.

It is still unknown why the man dubbed ''Wearside Jack'' instigated the hoax.