The investigation into the Yorkshire ripper murders has involved hundreds of police officers and thousands of man-hours.

BBC: 1981: Man arrested for Ripper murders

Following Sutcliffe's arrest in Sheffield last Friday, police told reporters they were confident they had apprehended the notorious Yorkshire Ripper.

BBC: 1981: Man arrested for Ripper murders

Yorkshire Ripper Peter Sutcliffe, from Bradford, now 59, was jailed for life in 1981 for the murder of 13 women.

BBC: NEWS | UK | England | West Yorkshire | Man still held over Ripper hoax

In the early hours of Thursday, 30 October 1975 she became the first victim of the Peter Sutcliffe, the Yorkshire Ripper.

BBC: Yorkshire Ripper victim's son rejects hanging

Evidence from the Yorkshire Ripper murders, the disappearance of Dewsbury youngster Shannon Matthews and the death of Lesley Molseed was also analysed at the laboratory.

BBC: Wetherby to Waco - DNA lab's demise

Evidence from the Yorkshire Ripper murders, the disappearance of Dewsbury youngster Shannon Matthews and the death of Lesley Molseed was dealt with at the Wetherby laboratory.

BBC: Wetherby forensic lab closure within days

After 25 years, police say they could no longer prosecute the man - dubbed Wearside Jack - who sent letters and a tape to police claiming to be the Yorkshire Ripper.

BBC: NEWS | UK | England | Hunt ended for 'Ripper' hoaxer

It's not the Yorkshire Ripper I'm signing, is it?

BBC: Tottenham sign defender William Gallas on one-year deal

Certainly not terrifying in the way that Fred and Rose West were, and the Yorkshire Ripper, the Moors Murderers, and all those other killers whose notoriety is such that the tabloids call them monsters.

BBC: Shipman in the dock

The hoaxer, who had an accent said to be from the Castletown area of Sunderland, sent police three letters and an audio tape at the height of the Yorkshire Ripper inquiry in 1978 and 1979.

BBC: NEWS | UK | England | Hunt ended for 'Ripper' hoaxer