A 50-year-old man has admitted being the notorious Yorkshire Ripper hoaxer known as Wearside Jack.
But John Humble, a former labourer from Flodden Road, Ford Estate, Sunderland, has denied intending to pervert the course of justice at Leeds Crown Court.
Mr Humble, who was not in court for the hearing, admitted writing letters and making a tape sent to police during the Ripper's reign of terror in the 1970s.
The police inquiry focused on the North East because of Wearside Jack's accent.
Reporting restrictions on the case were lifted by Judge James Stewart QC on Wednesday.
Mr Humble's defence counsel, David Taylor, told the court: "A defence statement has been drafted whereby the defence concedes that he wrote the letters and in fact made the tape.
"The issue now is not one of whether it actually was him, it's solely the question of intent."
Mr Taylor stressed that Mr Humble's not guilty pleas to four counts of perverting the course of justice still stood.
The case was adjourned for a trial on 20 March.
Two of the letters were sent directly to Assistant Chief Constable George Oldfield, who led the investigation in the late 1970s.
A third letter was sent to a national newspaper office in Manchester.
The audio tape, which purported to be from the murderer and taunted the police for not catching him, was played to a spellbound public by detectives in 1979.
Following the receipt of the letters and the tape, police effort was concentrated on the Sunderland area after senior officers decided the Wearside voice on the tape was that of the murderer.
The letters and tape were exposed as a hoax when Peter Sutcliffe was arrested in 1981 and confessed to being the ripper.
Yorkshire Ripper Peter Sutcliffe, from Bradford, now 59, was jailed for life in 1981 for the murder of 13 women.