Mr Hellawell has revealed that he has spent the past 10 years secretly reinvestigating at least 20 unsolved attacks and murders of women across Britain. His conclusion, he says, is that they bear all the hallmarks of Sutcliffe, who was jailed in 1981 for 13 murders and seven attempted murders.
His findings form part of a Network First documentary called "Silent Victims: The Untold Story of the Yorkshire Ripper" to be broadcast by Yorkshire Television on 10 December.
He says in the film that he believes these further attacks were by Sutcliffe, a lorry driver from Bradford, because of three factors. First, many of the victims were initally followed by their attacker who then chatted to them; second, they were (in some cases) battered with a ball-pein hammer; and third, those victims who survived have described their attacker as being swarthy with a dark beard, which fits Sutcliffe's appearance.
Mr Hellawell says that these 20 victims, including students and nurses, were not linked to Sutcliffe at the time because police were convinced that he was targeting prostitutes.
One victim, Tracy Browne, was 14 when she was attacked with a hammer by a man who followed her home. Mr Hellawell says he interviewed Sutcliffe in prison about the attack. He says: "He got to one stage where he said to me, `You're right: it sounds as if I've done them. The description is of me. It's in the right time-scale. The way that the person killed or attemped to kill is the way that I operated. Therefore it must be me.'"
Sutcliffe eventually admitted to attacking Ms Browne as well as to two attempted murders on Mr Hellawell's list, but the Director of Public Prosecutions ruled that it was not in the public interest to take him back to court. Mr Hellawell says: "He [Sutcliffe] related, all those years on, detailed circumstances of those attempted murders that only the criminal would know. He also remembered he put her [Ms Browne] over a fence. That hadn't been disclosed. We hadn't made that public at all. So only he would know that.
"I believe that there are others. And I have this feeling that he will one day tell me the truth."
One unsolved murder that he links with Sutcliffe is that of Debbie Schlesinger who was murdered in 1977 in Leeds, aged 18. No one has ever been charged with her killing.Reuse content